10-Q

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q

(Mark One)

þ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended June 30, 2015

OR

¨ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from to

Commission file number 1-7584

TRANSCONTINENTAL GAS PIPE LINE COMPANY, LLC

(Exact name of registrant as specified in its charter)

DELAWARE	74-1079400
(State or other jurisdiction of incorporation or organization)	(I.R.S. Employer Identification No.)
2800 POST OAK BOULEVARD HOUSTON, TEXAS	77056
(Address of principal executive offices)	(Zip Code)

Registrant’s telephone number, including area code: (713) 215-2000

NO CHANGE

(Former name, former address and former fiscal year, if changed since last report)

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  þ    No  ¨

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  þ   No  ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check one):

Large accelerated filer ¨ Accelerated filer ¨ Non-accelerated filer þ Smaller reporting company ¨

(Do not check if a smaller reporting company)

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes  ¨    No  þ

REGISTRANT MEETS THE CONDITIONS SET FORTH IN GENERAL INSTRUCTIONS H (1)(a) AND (b) OF FORM 10-Q AND IS THEREFORE FILING THIS FORM 10-Q WITH THE REDUCED DISCLOSURE FORMAT.

TRANSCONTINTENTAL GAS PIPE LINE COMPANY, LLC

Index

	Page
Part I. Financial Information:
Item 1. Financial Statements
Condensed Consolidated Statement of Comprehensive Income —Three and Six Months Ended June 30, 2015 and 2014	3
Condensed Consolidated Balance Sheet — June 30, 2015 and December 31, 2014	4
Condensed Consolidated Statement of Cash Flows — Six Months Ended June 30, 2015 and 2014	6
Notes to Condensed Consolidated Financial Statements	7
Item 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations	13
Item 4. Controls and Procedures	16
Part II. Other Information	16
Item 1. Legal Proceedings	16
Item 6. Exhibits	17

Forward Looking Statements

Certain matters contained in this report include “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. These forward-looking statements relate to anticipated financial performance, management’s plans and objectives for future operations, business prospects, outcome of regulatory proceedings, market conditions and other matters. We make these forward-looking statements in reliance on the safe harbor protections provided under the Private Securities Litigation Reform Act of 1995.

All statements, other than statements of historical facts, included in this report that address activities, events or developments that we expect, believe or anticipate will exist or may occur in the future are forward-looking statements. Forward-looking statements can be identified by various forms of words or phrases such as “anticipates,” “believes,” “seeks,” “could,” “may,” “should,” “continues,” “estimates,” “expects,” “assumes,” “forecasts,” “intends,” “might,” “goals,” “objectives,” “targets,” “planned,” “potential,” “projects,” “scheduled,” “will,” “guidance,” “outlook,” “in service date” or other similar expressions. These statements are based on management’s beliefs and assumptions and on information currently available to management and include, among others, statements regarding:

• Amounts and nature of future capital expenditures;

• Expansion and growth of our business and operations;

• Financial condition and liquidity;

• Business strategy;

• Cash flow from operations or results of operations;

• Rate case filings;

• Natural gas prices, supply and demand; and

• Demand for our services.

Forward-looking statements are based on numerous assumptions, uncertainties, and risks that could cause future events or results to be materially different from those stated or implied in this report. Many of the factors that will

1

determine these results are beyond our ability to control or predict. Specific factors that could cause actual results to differ from results contemplated by the forward-looking statements include, among others, the following:

• Availability of supplies, market demand, and volatility of prices;

• Inflation, interest rates, and general economic conditions (including future disruptions and volatility in the global credit markets and the impact of these events on our customers and suppliers);

• The strength and financial resources of our competitors and the effects of competition;

• Whether we are able to successfully identify, evaluate and execute investment opportunities;

• Development of alternative energy sources;

• The impact of operational and development hazards and unforeseen interruptions;

• Costs of, changes in, or the results of laws, government regulations (including safety and environmental regulations), environmental liabilities, litigation, and rate proceedings;

• Our allocated costs for defined benefit pension plans and other postretirement benefit plans sponsored by our affiliates;

• Changes in maintenance and construction costs;

• Changes in the current geopolitical situation;

• Our exposure to the credit risks of our customers and counterparties;

• Risks related to financing, including restrictions stemming from our debt agreements, future changes in our credit ratings and the availability and cost of capital;

• Risks associated with weather and natural phenomena including climate conditions;

• Acts of terrorism, including cybersecurity threats and related disruptions; and

• Additional risks described in our filings with the Securities and Exchange Commission (SEC).

Given the uncertainties and risk factors that could cause our actual results to differ materially from those contained in any forward-looking statement, we caution investors not to unduly rely on our forward-looking statements. We disclaim any obligations to and do not intend to update the above list or to announce publicly any revisions to any of the forward-looking statements to reflect future events or developments.

In addition to causing our actual results to differ, the factors listed above and referred to below may cause our intentions to change from those statements of intention set forth in this report. Such changes in our intentions may also cause our results to differ. We may change our intentions, at any time and without notice, based upon changes in such factors, our assumptions, or otherwise.

Because forward-looking statements involve risks and uncertainties, we caution that there are important factors, in addition to those listed above, that may cause actual results to differ materially from those contained in the forward-looking statements. For a detailed discussion of those factors, see Part I, Item 1A. Risk Factors in our Annual Report on Form 10-K for the year ended December 31, 2014.

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PART I — FINANCIAL INFORMATION

ITEM 1. Financial Statements.

TRANSCONTINENTAL GAS PIPE LINE COMPANY, LLC

CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME

(Thousands of Dollars)

(Unaudited)

	Three months ended   June 30,						Six months ended   June 30,
	2015			2014			2015			2014
Operating Revenues:
Natural gas sales	$	36,327		$	18,438		$	57,734		$	46,006
Natural gas transportation	319,356			283,979			641,916			584,360
Natural gas storage	34,322			34,665			69,467			71,260
Other	916			1,372			1,827			2,490
Total operating revenues	390,921			338,454			770,944			704,116
Operating Costs and Expenses:
Cost of natural gas sales	36,327			18,438			57,734			46,006
Cost of natural gas transportation	6,068			6,751			18,963			17,954
Operation and maintenance	63,225			63,905			131,508			124,338
Administrative and general	44,728			44,597			91,687			91,731
Depreciation and amortization	67,387			67,702			133,692			137,611
Taxes — other than income taxes	11,953			11,363			24,494			23,645
Other expense, net	14,171			5,955			31,986			13,406
Total operating costs and expenses	243,859			218,711			490,064			454,691
Operating Income	147,062			119,743			280,880			249,425
Other (Income) and Other Expenses:
Interest expense	20,656			21,197			41,463			43,156
Allowance for equity and borrowed funds used during construction (AFUDC)	(15,597		)	(4,391		)	(30,249		)	(7,373		)
Equity in earnings of unconsolidated affiliates	(1,234		)	(1,380		)	(2,753		)	(2,857		)
Miscellaneous other (income) expenses, net	440			(1,172		)	804			(770		)
Total other (income) and other expenses	4,265			14,254			9,265			32,156
Net Income	142,797			105,489			271,615			217,269
Other comprehensive income (loss):
Equity interest in unrealized gain (loss) on interest rate hedges (includes $83 and $86 for the three months ended and $167 and $170 for the six months ended June 30, 2015 and June 30, 2014, respectively, of accumulated other comprehensive income reclassification for equity interest in realized losses on interest rate hedges)	50			(41		)	(3		)	(3		)
Comprehensive Income	$	142,847		$	105,448		$	271,612		$	217,266

See accompanying notes.

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TRANSCONTINENTAL GAS PIPE LINE COMPANY, LLC

CONDENSED CONSOLIDATED BALANCE SHEET

(Thousands of Dollars)

(Unaudited)

	June 30, 2015		December 31, 2014
ASSETS
Current Assets:
Cash	$	—	$	173
Receivables:
Affiliates	431		654
Advances to affiliate	187,980		306,910
Trade and other	149,689		130,735
Transportation and exchange gas receivables	9,578		3,485
Inventories	58,985		66,699
Regulatory assets	103,255		77,810
Other	19,691		14,683
Total current assets	529,609		601,149
Investments, at cost plus equity in undistributed earnings	46,562		47,050
Property, Plant and Equipment:
Natural gas transmission plant	10,275,813		9,645,382
Less-Accumulated depreciation and amortization	3,365,599		3,257,844
Total property, plant and equipment, net	6,910,214		6,387,538
Other Assets:
Regulatory assets	222,983		239,080
Other	80,830		75,066
Total other assets	303,813		314,146
Total assets	$	7,790,198	$	7,349,883

(continued)

See accompanying notes.

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TRANSCONTINENTAL GAS PIPE LINE COMPANY, LLC

CONDENSED CONSOLIDATED BALANCE SHEET

(Thousands of Dollars)

(Unaudited)

	June 30, 2015			December 31, 2014
LIABILITIES AND OWNER’S EQUITY
Current Liabilities:
Payables:
Affiliates	$	46,413		$	37,688
Trade and other	291,300			268,740
Transportation and exchange gas payables	3,832			4,701
Accrued liabilities	97,495			104,105
Long-term debt due within one year	200,000			—
Total current liabilities	639,040			415,234
Long-Term Debt	1,228,568			1,428,495
Other Long-Term Liabilities:
Asset retirement obligations	276,957			280,031
Regulatory liabilities	354,219			326,083
Other	76,490			35,728
Total other long-term liabilities	707,666			641,842
Contingent Liabilities and Commitments (Note 2)
Owner’s Equity:
Member’s capital	2,836,499			2,524,499
Retained earnings	2,378,543			2,339,928
Accumulated other comprehensive loss	(118		)	(115		)
Total owner’s equity	5,214,924			4,864,312
Total liabilities and owner’s equity	$	7,790,198		$	7,349,883

See accompanying notes.

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TRANSCONTINENTAL GAS PIPE LINE COMPANY, LLC

CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS

(Thousands of Dollars)

(Unaudited)

	Six months ended June 30,
	2015			2014
Cash flows from operating activities:
Net income	$	271,615		$	217,269
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	133,692			137,153
Allowance for equity funds used during construction (equity AFUDC)	(23,123		)	(5,469		)
Changes in operating assets and liabilities:
Receivables — affiliates	223			1,808
— trade and other	(18,954		)	37,509
Transportation and exchange gas receivable	(6,093		)	2,506
Inventories	7,714			(26,632		)
Payables — affiliates	8,725			15,596
— trade	9,319			(103,555		)
Accrued liabilities	(9,048		)	(10,567		)
Reserve for rate refunds	—			20,075
Asset retirement obligation removal costs	(972		)	(7,555		)
Other, net	13,482			(4,602		)
Net cash provided by operating activities	386,580			273,536
Cash flows from financing activities:
Cash distributions to parent	(233,000		)	(235,000		)
Cash contributions from parent	312,000			94,000
Other, net	13,539			6,830
Net cash provided by (used in) financing activities	92,539			(134,170		)
Cash flows from investing activities:
Property, plant and equipment additions, net of equity AFUDC*	(633,476		)	(219,971		)
Contributions and advances for construction costs	32,600			23,801
Disposal of property, plant and equipment, net	620			2,958
Advances to affiliate, net	118,930			59,578
Return of capital from unconsolidated affiliates	902			469
Purchase of ARO Trust investments	(42,022		)	(35,012		)
Proceeds from sale of ARO Trust investments	27,075			27,411
Proceeds from insurance	14,804			—
Other, net	1,275			1,414
Net cash used in investing activities	(479,292		)	(139,352		)
Increase (decrease) in cash	(173		)	14
Cash at beginning of period	173			113
Cash at end of period	$	—		$	127
*       Increase to property, plant and equipment, net of equity AFUDC	$	(630,346	)	$	(253,298	)
Changes in related accounts payable and accrued liabilities	(3,130		)	33,327
Property, plant and equipment additions, net of equity AFUDC	$	(633,476	)	$	(219,971	)

See accompanying notes.

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TRANSCONTINENTAL GAS PIPE LINE COMPANY, LLC

NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS

(Unaudited)

1. BASIS OF PRESENTATION

In this report, Transco (which includes Transcontinental Gas Pipe Line Company, LLC and, unless the context otherwise requires, all of our majority-owned subsidiaries) is at times referred to in the first person as “we,” “us” or “our.”

Transco is indirectly owned by Williams Partners L.P. (WPZ), a publicly traded Delaware limited partnership, which is consolidated by The Williams Companies, Inc. (Williams). On February 2, 2015, WPZ was merged into Access Midstream Partners, L.P. (ACMP), another publicly traded limited partnership consolidated by Williams. ACMP was the surviving partnership and was subsequently renamed Williams Partners, L.P. At June 30, 2015, Williams holds an approximate 60 percent interest in WPZ, comprised of an approximate 58 percent limited partner interest and all of the 2 percent general partner interest.

General

The condensed consolidated unaudited financial statements include our accounts and the accounts of the subsidiaries we control. Companies in which we and our subsidiaries own 20 percent to 50 percent of the voting common stock or otherwise exercise significant influence over operating and financial policies of the company are accounted for under the equity method. The equity method investments as of June 30, 2015 and December 31, 2014 consist of Cardinal Pipeline Company, LLC (Cardinal) with an ownership interest of approximately 45 percent and Pine Needle LNG Company, LLC (Pine Needle) with an ownership interest of 35 percent. We received distributions associated with our equity method investments totaling $3.2 million and $4.4 million in the six months ended June 30, 2015 and June 30, 2014, respectively. Included in the distributions are $0.9 million and $0.5 million return of capital in 2015 and 2014, respectively.

The condensed consolidated unaudited financial statements have been prepared from our books and records. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (GAAP) have been condensed or omitted in this Form 10-Q pursuant to Securities and Exchange Commission rules and regulations. The condensed consolidated unaudited financial statements include all normal recurring adjustments and others which, in the opinion of our management, are necessary to present fairly our interim financial statements. These condensed consolidated unaudited financial statements should be read in conjunction with the consolidated financial statements and the notes thereto included in our 2014 Annual Report on Form 10-K.

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated unaudited financial statements and accompanying notes. Actual results could differ from those estimates.

Accounting Standards Issued But Not Yet Adopted

In July 2015, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2015-11 “Simplifying the Measurement of Inventory” (ASU 2015-11). ASU 2015-11 simplifies the guidance on the subsequent measurement of inventory, excluding inventory measured using last-in, first out or the retail inventory method. Under the new standard, in scope inventory should be measured at the lower of cost and net realizable value. The new standard is effective for interim and annual periods beginning after December 15, 2016, with early adoption permitted. We are evaluating the impact of the new standard.

In April 2015, the FASB issued ASU 2015-3 “Interest - Imputation of Interest: Simplifying the Presentation of Debt Issuance Costs” (ASU 2015-3). ASU 2015-3 simplifies the presentation of debt issuance costs by requiring such costs be presented as a deduction from the corresponding debt liability. The guidance is effective for financial statements issued for reporting periods beginning after December 15, 2015, and interim periods within the reporting periods and requires retrospective presentation. We are evaluating the impact of the new standard.

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In February 2015, the FASB issued ASU 2015-2 “Amendments to the Consolidation Analysis” (ASU 2015-2). ASU 2015-2 alters the models used to determine consolidation conclusions for certain entities, including limited partnerships, and may require additional disclosures. The ASU is effective for financial statements issued for reporting periods beginning after December 15, 2015, and interim periods within the reporting periods with either retrospective or modified retrospective presentation allowed. We are currently evaluating the impact of the new standard on our consolidated financial statements.

In May 2014, the FASB issued ASU 2014-09 establishing Accounting Standards Codification Topic 606, “Revenue from Contracts with Customers” (ASC 606). ASC 606 establishes a comprehensive new revenue recognition model designed to depict the transfer of goods or services to a customer in an amount that reflects the consideration the entity expects to be entitled to receive in exchange for those goods or services and requires significantly enhanced revenue disclosures. The standard is effective for annual reporting periods beginning after December 15, 2017, and interim periods within the reporting period. ASC 606 allows either full retrospective or modified retrospective transition and early adoption is permitted for annual periods beginning after December 15, 2016. We continue to evaluate both the impact of this new standard on our consolidated financial statements and the transition method we will utilize for adoption.

2. CONTINGENT LIABILITIES AND COMMITMENTS

Rate Matters

General rate case (Docket No. RP06-569) On August 31, 2006, we submitted to the Federal Energy Regulatory Commission (FERC) a general rate filing principally designed to recover increased costs. The rates became effective March 1, 2007, subject to refund and the outcome of a hearing. All issues in this proceeding except one have been resolved by settlement.

The one issue reserved for litigation or further settlement relates to our proposal to change the design of the rates for service under one of our storage rate schedules, which was implemented subject to refund on March 1, 2007. A hearing on that issue was held before a FERC Administrative Law Judge (ALJ) in July 2008. In November 2008, the ALJ issued an initial decision in which he determined that our proposed incremental rate design is unjust and unreasonable. On January 21, 2010, the FERC reversed the ALJ’s initial decision and approved our proposed incremental rate design. Certain parties sought rehearing of the FERC’s order and, on April 2, 2012, the FERC denied the rehearing request. On June 1, 2012, one of the parties filed an appeal in the U.S. Court of Appeals for the D.C. Circuit (D.C. Circuit). On February 21, 2014, the D.C. Circuit issued an opinion that vacated and remanded the FERC's order because the FERC did not adequately support its conclusions. On October 16, 2014, the FERC issued an order establishing a "paper hearing" and requesting briefs on certain questions raised by the D.C. Circuit's opinion. Parties to the proceeding filed initial and reply briefs on February 6, 2015 and March 6, 2015, respectively. We intend to continue to pursue approval of our proposed rate design. If we are unsuccessful, it is reasonably possible that refunds could be as much as $17 million at June 30, 2015.

Environmental Matters

We have had studies underway for many years to test some of our facilities for the presence of toxic and hazardous substances such as polychlorinated biphenyls (PCBs) and mercury to determine to what extent, if any, remediation may be necessary. We have also similarly evaluated past on-site disposal of hydrocarbons at a number of our facilities. We have worked closely with and responded to data requests from the U.S. Environmental Protection Agency (EPA) and state agencies regarding such potential contamination of certain of our sites. On the basis of the findings to date, we estimate that environmental assessment and remediation costs under various federal and state statutes will total approximately $4 million to $6 million (including both expense and capital expenditures), measured on an undiscounted basis, and will substantially be spent over the next three to four years. This estimate depends on a number of assumptions concerning the scope of remediation that will be required at certain locations and the cost of the remedial measures. We are conducting environmental assessments and implementing a variety of remedial measures that may result in increases or decreases in the total estimated costs. At June 30, 2015, we had a balance of approximately $1.8 million for the expense portion of these estimated costs recorded in current liabilities ($0.8 million) and other long-term liabilities ($1.0 million) in the accompanying Condensed Consolidated Balance Sheet. At December 31, 2014, we had a balance

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of approximately $2.7 million for the expense portion of these estimated costs recorded in current liabilities ($0.8 million) and other long-term liabilities ($1.9 million) in the accompanying Condensed Consolidated Balance Sheet.

We have been identified as a potentially responsible party (PRP) at various Superfund and state waste disposal sites. Based on present volumetric estimates and other factors, our estimated aggregate exposure for remediation of these sites is less than $0.5 million. The estimated remediation costs for all of these sites are included in the $4 million to $6 million range discussed above. Liability under the Comprehensive Environmental Response, Compensation and Liability Act and applicable state law can be joint and several with other PRPs. Although volumetric allocation is a factor in assessing liability, it is not necessarily determinative; thus, the ultimate liability could be substantially greater than the amounts described above.

In March 2008, the EPA promulgated a new, lower National Ambient Air Quality Standard (NAAQS) for ground-level ozone. In May 2012, the EPA completed designation of new eight-hour ozone non-attainment areas. Several facilities are located in 2008 ozone non-attainment areas. To date, no federal actions have been proposed to mandate additional emission controls at these facilities. Pursuant to recently proposed state regulatory actions associated with implementation of the 2008 ozone standard, we anticipate that some facilities may be subject to increased controls within five years. As a result, the cost of additions to property, plant, and equipment is expected to increase. We are unable at this time to estimate with any certainty the cost of additions that may be required to meet the proposed regulations.

In December 2014, the EPA proposed to further reduce the ground-level ozone NAAQS from the March 2008 levels; the EPA is anticipated to finalize any revisions in late 2015. Revisions to the ozone NAAQS will result in additional federal and state regulatory actions that may impact our operations. As a result, the cost of additions to property, plant and equipment is expected to increase. We are unable at this time to estimate with any certainty the cost of additions that may be required to meet new regulations.

On January 22, 2010, the EPA set a new one-hour nitrogen dioxide (NO2) NAAQS. The effective date of the new NO2 standard was April 12, 2010. On January 20, 2012, the EPA determined pursuant to available information that no area in the country is violating the 2010 NO2 NAAQS and thus designated all areas of the country as “unclassifiable/attainment.” Also, at that time, the EPA noted its plan to deploy an expanded NO2 monitoring network beginning in 2013. However, on October 5, 2012, the EPA proposed a graduated implementation of the monitoring network between January 1, 2014 and January 1, 2017. Once three years of data is collected from the new monitoring network, the EPA will reassess attainment status with the one-hour NO2 NAAQS. Until that time, the EPA or states may require ambient air quality modeling on a case by case basis to demonstrate compliance with the NO2 standard. Because we are unable to predict the outcome of the EPA’s or states’ future assessment using the new monitoring network, we are unable to estimate the cost of additions that may be required to meet this regulation.

We consider prudently incurred environmental assessment and remediation costs and the costs associated with compliance with environmental standards to be recoverable through rates. To date, we have been permitted recovery of environmental costs, and it is our intent to continue seeking recovery of such costs through future rate filings. As a result, as estimated costs of environmental assessment and remediation are incurred, they are recorded as regulatory assets in the Condensed Consolidated Balance Sheet until collected through rates. At June 30, 2015, we had a balance of approximately $1.1 million of uncollected environmental related regulatory assets recorded in current assets in the accompanying Condensed Consolidated Balance Sheet. At December 31, 2014, we had a balance of approximately $1.7 million of uncollected environmental related regulatory assets recorded in current assets ($1.2 million) and other assets ($0.5 million) in the accompanying Condensed Consolidated Balance Sheet.

Other Matters

Various other proceedings are pending against us and are considered incidental to our operations.

Summary

We estimate that for all matters for which we are able to reasonably estimate a range of loss, including those noted above and others that are not individually significant, our aggregate reasonably possible losses beyond amounts accrued for all of our contingent liabilities are immaterial to our expected future annual results of operations, liquidity

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and financial position. These calculations have been made without consideration of any potential recovery from third parties. We have disclosed all significant matters for which we are unable to reasonably estimate a range of possible loss.

3. DEBT AND FINANCING ARRANGEMENTS

Credit Facility

On February 2, 2015, the previous credit facility to which we were a party was terminated in connection with the merger of the former Williams Partners L.P. with and into ACMP. Simultaneously, we along with WPZ and Northwest Pipeline LLC (Northwest), as co-borrowers, entered into a new $3.5 billion credit facility. Total letter of credit capacity available to WPZ under the $3.5 billion credit facility is $1.125 billion. We may borrow up to $500 million under this credit facility to the extent not otherwise utilized by WPZ and Northwest. At June 30, 2015, no letters of credit have been issued and no loans are outstanding under our credit facility.

WPZ participates in a commercial paper program, and WPZ management considers amounts outstanding under this program to be a reduction of available capacity under the credit facility. The program allows a maximum outstanding amount at any time of $3 billion of unsecured commercial paper notes. At June 30, 2015, WPZ had approximately $1.7 billion of commercial paper outstanding.

Long-Term Debt Due Within One Year

The long-term debt due within one year at June 30, 2015 is associated with the $200 million of 6.4 percent notes that mature on April 15, 2016.

4. ARO TRUST

Available-for-Sale Investments

We are entitled to collect in rates the amounts necessary to fund our asset retirement obligations (ARO). We deposit monthly, into an external trust account (ARO Trust), the revenues specifically designated for ARO. The ARO Trust carries a moderate risk portfolio. We measure the financial instruments held in our ARO Trust at fair value. However, in accordance with the ASC Topic 980, Regulated Operations, both realized and unrealized gains and losses of the ARO Trust are recorded as regulatory assets or liabilities.

Effective March 1, 2013, the annual funding obligation is approximately $36.4 million, with deposits made monthly.

Investments in available-for-sale securities within the ARO Trust at fair value were as follows (in millions):

	June 30, 2015				December 31, 2014
	Amortized Cost Basis		Fair Value		Amortized Cost Basis		Fair Value
Cash and Money Market Funds	$	5.0	$	5.0	$	2.1	$	2.1
U.S. Equity Funds	18.0		22.2		15.0		19.0
International Equity Funds	11.7		12.2		8.0		8.2
Municipal Bond Funds	23.0		23.2		17.7		18.2
Total	$	57.7	$	62.6	$	42.8	$	47.5

5. FAIR VALUE MEASUREMENTS

The following table presents, by level within the fair value hierarchy, certain of our financial assets and liabilities. The carrying values of cash, short-term financial assets (advances to affiliate) that have variable interest rates, accounts

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receivable and accounts payable approximate fair value because of the short-term nature of these instruments. Therefore, these assets and liabilities are not presented in the following table.

							Fair Value Measurements Using
	Carrying Amount			Fair Value			Quoted Prices In Active Markets for Identical Assets (Level  1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)
	(Millions)
Assets (liabilities) at June 30, 2015:
Measured on a recurring basis:
ARO Trust investments	$	62.6		$	62.6		$	62.6	$	—		$	—
Additional disclosures:
Notes receivable	2.5			2.5			—		2.5			—
Long-term debt	(1,428.6		)	(1,546.7		)	—		(1,546.7		)	—
Assets (liabilities) at December 31, 2014:
Measured on a recurring basis:
ARO Trust investments	$	47.5		$	47.5		$	47.5	$	—		$	—
Additional disclosures:
Notes receivable	3.8			3.8			—		3.8			—
Long-term debt	(1,428.5		)	(1,506.4		)	—		(1,506.4		)	—

Fair Value of Methods

The following methods and assumptions were used to estimate the fair value of each class of financial instruments for which it is practicable to estimate that value:

ARO Trust investments — We deposit a portion of our collected rates, pursuant to the terms of the Docket No. RP12-993 rate case settlement, into the ARO Trust, which is specifically designated to fund future asset retirement obligations. The ARO Trust invests in a portfolio of actively traded mutual funds that are measured at fair value on a recurring basis based on quoted prices in an active market, are classified as available-for-sale and are reported in Other Assets-Other in the Condensed Consolidated Balance Sheet. However, both realized and unrealized gains and losses are ultimately recorded as regulatory assets or liabilities. See Note 4 for more information regarding the ARO Trust.

Notes receivable — The disclosed fair value of our notes receivable is determined by an income approach, which considers the underlying contract amounts and our assessment of our ability to recover these amounts. The current portion is reported in Trade and other receivables, and the noncurrent portion is reported in Other Assets-Other in the Condensed Consolidated Balance Sheet.

Long-term debt — The disclosed fair value of our long-term debt is determined by a market approach using broker quoted indicative period-end bond prices. The quoted prices are based on observable transactions in less active markets for our debt or similar instruments.

Reclassifications of fair value between Level 1, Level 2, and Level 3 of the fair value hierarchy, if applicable, are made at the end of each quarter. No transfers between Level 1 and Level 2 occurred during the six months ended June 30, 2015 or 2014.

6. TRANSACTIONS WITH AFFILIATES

We are a participant in WPZ’s cash management program, and we make advances to and receive advances from WPZ. At June 30, 2015 and December 31, 2014, our advances to WPZ totaled approximately $188.0 million and $306.9 million, respectively. These advances are represented by demand notes and are classified as Current Assets in the

11

accompanying Condensed Consolidated Balance Sheet. Advances are stated at the historical carrying amounts. Interest income is recognized when chargeable and collectability is reasonably assured. The interest rate on these intercompany demand notes is based upon the daily overnight investment rate paid on WPZ’s excess cash at the end of each month. At June 30, 2015, the interest rate was 0.01 percent.

Included in Operating Revenues in the accompanying Condensed Consolidated Statement of Comprehensive Income are revenues received from affiliates of $0.7 million and $1.9 million for the three and six months ended June 30, 2015, respectively, and $1.5 million and $2.8 million for the three and six months ended June 30, 2014, respectively. The rates charged to provide sales and services to affiliates are the same as those that are charged to similarly-situated nonaffiliated customers.

Included in Cost of natural gas sales in the accompanying Condensed Consolidated Statement of Comprehensive Income are cost of gas purchased from affiliates of $1.7 million and $4.2 million for the three and six months ended June 30, 2015, respectively and $3.4 million and $6.8 million for the three and six months ended June 30, 2014, respectively. All gas purchases are made at market or contract prices.

We have no employees. Services necessary to operate our business are provided to us by Williams and certain affiliates of Williams. We reimburse Williams and its affiliates for all direct and indirect expenses incurred or payments made (including salary, bonus, incentive compensation and benefits) in connection with these services. Employees of Williams also provide general, administrative and management services to us, and we are charged for certain administrative expenses incurred by Williams. These charges are either directly identifiable or allocated to our assets. Direct charges are for goods and services provided by Williams at our request. Allocated charges are based on a three-factor formula, which considers revenues; property, plant and equipment; and payroll. In management’s estimation, the allocation methodologies used are reasonable and result in a reasonable allocation to us of our costs of doing business incurred by Williams. We were billed $81.6 million and $162.6 million in the three and six months ended June 30, 2015, respectively, and $74.5 million and $149.7 million in the three and six months ended June 30, 2014, respectively, for these services. Such expenses are primarily included in Administrative and general and Operation and maintenance expenses in the accompanying Condensed Consolidated Statement of Comprehensive Income.

We provide services to certain of our affiliates. We recorded reductions in operating expenses for services provided to and reimbursed by our affiliates of $1.5 million and $2.7 million for the three and six months ended June 30, 2015, respectively, and $1.9 million and $3.2 million for the three and six months ended June 30, 2014, respectively. In the first quarter of 2014, pursuant to construction agreements, we received pre-payments from Williams Field Services Group, LLC of $4.2 million associated with capital projects.

We made equity distributions totaling $233.0 million and $235.0 million during the six months ended June 30, 2015 and 2014, respectively. During July 2015, we made an additional distribution of $141.0 million. Our parent made contributions to us totaling $312.0 million and $94.0 million in the six months ended June 30, 2015 and 2014, respectively, to fund a portion of our expenditures for additions to property, plant and equipment. In July 2015, our parent made an additional $179.0 million contribution to us.

7. OTHER

For the six months ended June 30, 2014, we capitalized $3.5 million of project feasibility cost associated with various projects, which had been expensed in prior periods in Other expense, net, upon determining that the projects were probable of development.

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ITEM 2. Management’s Discussion and Analysis of Financial Condition and Results of Operations

General

The following discussion should be read in conjunction with the Consolidated Financial Statements, Notes and Management’s Discussion and Analysis contained in Items 7 and 8 of our 2014 Annual Report on Form 10-K and with the Condensed Consolidated Financial Statements and Notes contained in this Form 10-Q.

RESULTS OF OPERATIONS

Operating Income and Net Income

Operating income for the six months ended June 30, 2015 was $280.9 million compared to $249.4 million for the six months ended June 30, 2014. Net income for the six months ended June 30, 2015 was $271.6 million compared to $217.3 million for the six months ended June 30, 2014. The increase in Operating income of $31.5 million (12.6 percent) was primarily due to higher Natural gas transportation revenues in the first six months of 2015 compared to the same period in 2014, partly offset by an increase in Operating Costs and Expenses, as discussed below. The increase in Net income of $54.3 million (25.0 percent) was mostly attributable to the increase in Operating income and a favorable change in net expenses in Other (Income) and Other Expenses, as discussed below.

Sales Revenues

Operating revenues: Natural gas sales increased $11.7 million (25.4 percent) for the six months ended June 30, 2015 compared to the same period in 2014. The increase was due to higher cash-out sales. Cash-out sales are offset in our cost of natural gas sold and therefore had no impact on our operating income or results of operations.

Transportation Revenues

Operating revenues: Natural gas transportation for the six months ended June 30, 2015 increased $57.5 million (9.8 percent) over the same period in 2014. The increase was primarily due to higher transportation reservation revenues related to new incremental projects of $55.6 million (primarily due to $26.4 million from our Leidy Southeast project placed in partial service in March 2015, $11.0 million from our Virginia Southside project placed in partial service in December 2014 and $10.5 million from our Rockaway project placed in service in May 2015).

Storage Revenues

Operating revenues: Natural gas storagefor the six months ended June 30, 2015 decreased $1.8 million (2.5 percent) over the same period in 2014. The decrease was primarily due to lower rates in 2015 compared to 2014.

Operating Costs and Expenses

Excluding the Cost of natural gas sales, which is directly offset in revenues, of $57.7 million for the six months ended June 30, 2015 and $46.0 million for the comparable period in 2014, our operating costs and expenses for the six months ended June 30, 2015 increased approximately $23.6 million (5.8 percent) from the comparable period in 2014. This increase was primarily attributable to:

• An $18.6 million (138.8 percent) increase in Other expense, net primarily due to a $6.9 million unfavorable change in the deferral of ARO-related depreciation to a regulatory asset, a $5.9 million increase in project development costs partly due to the capitalization of $3.5 million feasibility costs recorded in 2014, and $4.0 million of expense to establish a regulatory liability associated with rate collections in excess of our pension funding obligation.

• A $7.2 million (5.8 percent) increase in Operation and maintenance costs primarily due to a $4.7 million increase in labor and related costs and a $1.7 million increase in miscellaneous contractual services costs primarily due to general maintenance and safety review.

• Partially offset by a $3.9 million (2.8 percent) decrease in Depreciation and amortization costs primarily due to a decrease in offshore ARO-related depreciation expense.

Other (Income) and Other Expenses

Other (income) and other expenses for the six months ended June 30, 2015 had a favorable change of $22.9 million (71.1 percent) over the same period in 2014 primarily due to a $22.8 million increase in AFUDC due to increased spending on various expansion projects.

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Pipeline Expansion Projects

Rockaway Delivery Lateral

The Rockaway Delivery Lateral Project involves the construction of a three-mile offshore lateral to National Grid’s distribution system in New York. In May 2014, we received approval from the FERC for the project. We placed the project into service during the second quarter of 2015, which enabled us to begin providing 647 Mdth/d of firm delivery service to National Grid through the Rockaway Delivery Lateral.

Northeast Connector

The Northeast Connector Project involves an expansion of our existing natural gas transmission system from southeastern Pennsylvania to the proposed Rockaway Delivery Lateral. In May 2014, we received approval from the FERC for the project. On December 1, 2014, we placed a portion of the project into service, which enabled us to begin providing 65 Mdth/d of additional firm transportation service from Station 195 in Pennsylvania to the Rockaway Delivery Lateral junction. We placed the remainder of the project into service during the second quarter of 2015. In total, the project increased capacity by 100 Mdth/d.

Mobile Bay South III

The Mobile Bay South III Project involves an expansion of the Mobile Bay line south from Station 85 in west central Alabama to delivery points along the line. In April 2014, we received approval from the FERC for the project. On April 1, 2015, the project was placed into service, which enabled us to begin providing 225 Mdth/d of additional firm transportation service through the Mobile Bay Lateral.

Virginia Southside

The Virginia Southside Project involves an expansion of our existing mainline natural gas transmission system together with a new lateral to provide incremental firm transportation capacity from the Zone 6 Station 210 Pooling Point in New Jersey to Dominion Virginia Power’s proposed power station in Brunswick County, Virginia, and to both our Cascade Creek interconnection with East Tennessee Natural Gas and our Pleasant Hill delivery point to Piedmont Natural Gas Company, Inc. in North Carolina. In November 2013, we received approval from the FERC for the project. On December 1, 2014, we placed a portion of the project into service, which enabled us to begin providing 250 Mdth/d of additional firm transportation service through the mainline portion of the project on an interim basis, until the in-service date of the project as a whole. We plan to place the remainder of the project into service during the third quarter of 2015 (the original target in-service date for the project). In total, the project is expected to increase capacity by 270 Mdth/d.

Leidy Southeast

The Leidy Southeast Project involves an expansion of our existing natural gas transmission system from the Marcellus Shale production region on the Leidy Line in Pennsylvania to the Station 85 Pooling Point in Choctaw County, Alabama. In December 2014, we received approval from the FERC for the project. On March 1, 2015, we began providing firm transportation service through the mainline portion of the project (from the Station 210 Pooling Point in New Jersey to the Station 85 Pooling Point) on an interim basis, until the in-service date of the project as a whole. We plan to place the remainder of the project into service during the fourth quarter of 2015, and it is expected to increase capacity by 525 Mdth/d.

Rock Springs

The Rock Springs Expansion Project involves an expansion of our existing natural gas transmission system southbound from the Zone 6 Station 210 Pooling Point in New Jersey along with a new, eleven-mile lateral to Old Dominion Electric Cooperative's proposed Wildcat Point generation facility in Cecil County, Maryland. In March 2015, we received approval from FERC for the project. We plan to place the project into service during the third quarter of 2016, assuming timely receipt of all other necessary regulatory approvals, and it is expected to increase capacity by 192 Mdth/d.

Hillabee

The Hillabee Expansion Project involves an expansion of our existing natural gas transmission system from our Station 85 Pooling Point in Choctaw County, Alabama to a proposed new interconnection with Sabal Trail Transmission's system in Tallapoosa County, Alabama. The project will be constructed in phases, and all of the project expansion capacity will be leased to Sabal Trail Transmission. We filed an application with the FERC in November 2014 for approval of the

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initial phases of the project. We plan to place the initial phases of the project into service during the second quarters of 2017 and 2020, assuming timely receipt of all necessary regulatory approvals, and together they are expected to increase capacity by 1,025 Mdth/d.

Gulf Trace

The Gulf Trace Expansion Project involves an expansion of our existing natural gas transmission system together with greenfield facilities to provide incremental firm transportation capacity from Station 65 in St. Helena Parish, Louisiana westward to a new interconnection with Sabine Pass Liquefaction in Cameron Parish, Louisiana. We filed an application with the FERC in December 2014 for approval of the project. We plan to place the project into service during the first half of 2017, assuming timely receipt of all necessary regulatory approvals, and it is expected to increase capacity by 1,200 Mdth/d.

Dalton

The Dalton Expansion Project involves an expansion of our existing natural gas transmission system together with greenfield facilities to provide incremental firm transportation capacity from the Zone 6 Station 210 Pooling Point in New Jersey to markets in northwest Georgia. We filed an application with the FERC in March 2015 for approval of the project. We plan to place the project into service in 2017, assuming timely receipt of all necessary regulatory approvals, and it is expected to increase capacity by 448 Mdth/d.

Atlantic Sunrise

The Atlantic Sunrise Project involves an expansion of our existing natural gas transmission system together with greenfield facilities to provide incremental firm transportation capacity from the northeastern Marcellus producing area to markets along our mainline as far south as Station 85 in Alabama. We filed an application with the FERC in March 2015 for approval of the project. We plan to place the project into service during the second half of 2017, assuming timely receipt of all necessary regulatory approvals, and it is expected to increase capacity by 1,700 Mdth/d.

Garden State

The Garden State Expansion Project involves an expansion of our existing natural gas transmission system to provide incremental firm transportation capacity from our Zone 6 Station 210 Pooling Point in New Jersey to a new interconnection on our Trenton Woodbury Lateral in Burlington County, New Jersey. The project will be constructed in phases. We filed an application with the FERC in February 2015 for approval of the project. We plan to place the initial phase of the project into service during the fourth quarter of 2016 and the remaining portion of the project into service during the third quarter of 2017, assuming timely receipt of all necessary regulatory approvals. The project is expected to increase capacity by 180 Mdth/d.

Virginia Southside II

The Virginia Southside II Expansion Project involves an expansion of our existing natural gas transmission system together with greenfield facilities to provide incremental firm transportation capacity from the Zone 6 Station 210 Pooling Point in New Jersey and the Zone 5 Station 165 Pooling Point in Virginia to a proposed delivery point on a new lateral off of our Brunswick Lateral in Virginia. We filed an application with the FERC in March 2015 for approval of the project. We plan to place the project into service during the fourth quarter of 2017, assuming timely receipt of all necessary regulatory approvals, and it is expected to increase capacity by 250 Mdth/d.

New York Bay

The New York Bay Expansion Project involves an expansion of our existing natural gas transmission system to provide incremental firm transportation capacity from Station 195 in Pennsylvania to the Rockaway Delivery Lateral transfer point and the Narrows meter station in Richmond County, New York. We filed an application with the FERC in July 2015 for approval of the project. We plan to place the project into service during the fourth quarter of 2017, assuming timely receipt of all necessary regulatory approvals, and it is expected to increase capacity by 115 Mdth/d.

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ITEM 4. Controls and Procedures

Our management, including our Senior Vice President - Atlantic-Gulf and our Vice President and Chief Accounting Officer, does not expect that our disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) of the Securities Exchange Act) (Disclosure Controls) or our internal control over financial reporting (Internal Controls)will prevent all errors and all fraud. A control system, no matter how well conceived and operated, can provide only reasonable, not absolute, assurance that the objectives of the control system are met. Further, the design of a control system must reflect the fact that there are resource constraints, and the benefits of controls must be considered relative to their costs. Because of the inherent limitations in all control systems, no evaluation of controls can provide absolute assurance that all control issues and instances of fraud, if any, within the company have been detected. These inherent limitations include the realities that judgments in decision-making can be faulty, and that breakdowns can occur because of simple error or mistake. Additionally, controls can be circumvented by the individual acts of some persons, by collusion of two or more people, or by management override of the control. The design of any system of controls also is based in part upon certain assumptions about the likelihood of future events, and there can be no assurance that any design will succeed in achieving its stated goals under all potential future conditions. Because of the inherent limitations in a cost-effective control system, misstatements due to error or fraud may occur and not be detected. We monitor our Disclosure Controls and Internal Controls and make modifications as necessary; our intent in this regard is that the Disclosure Controls and Internal Controls will be modified as systems change and conditions warrant.

Evaluation of Disclosure Controls and Procedures

An evaluation of the effectiveness of the design and operation of our Disclosure Controls was performed as of the end of the period covered by this report. This evaluation was performed under the supervision and with the participation of our management, including our Senior Vice President - Atlantic-Gulf and our Vice President and Chief Accounting Officer. Based upon that evaluation, our Senior Vice President - Atlantic-Gulf and our Vice President and Chief Accounting Officer concluded that these Disclosure Controls are effective at a reasonable assurance level.

Changes in Internal Control Over Financial Reporting

There have been no changes during the second quarter of 2015 that have materially affected, or are reasonably likely to materially affect, our Internal Control over Financial Reporting.

PART II — OTHER INFORMATION.

ITEM 1. Legal Proceedings

The information called for by this item is provided in Note 2 of the Notes to Condensed Consolidated Financial Statements included under Part I, Item 1. Financial Statements of this report, which information is incorporated by reference into this item.

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ITEM 6. Exhibits

The following instruments are included as exhibits to this report.

Exhibit Number	Description
2	Certificate of Conversion dated December 22, 2008 and effective December 31, 2008 (filed on February 24, 2011 as Exhibit 2.1 to our report Form 10-K and incorporated herein by reference).
3.1	Certificate of Formation dated December 22, 2008 and effective December 31, 2008 (filed on February 24, 2011 as Exhibit 3.1 to our report Form 10-K and incorporated herein by reference).
3.2	Amended and Restated Operating Agreement of Transcontinental Gas Pipe Line Company, LLC dated February 17, 2010 (filed on October 28, 2010 as Exhibit 3.2 to our Form 10-Q and incorporated herein by reference).
31.1*	Certification of Principal Executive Officer pursuant to Rules 13a-14(a) and 15d-14(a) promulgated under the Securities Exchange Act of 1934, as amended, and Item 601(b)(31) of Regulation S-K, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.
31.2*	Certification of Principal Financial Officer pursuant to Rules 13a-14(a) and 15d-14(a) promulgated under the Securities Exchange Act of 1934, as amended, and Item 601(b)(31) of Regulation S-K, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.
32**	Certification of Principal Executive Officer and Principal Financial Officer pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.
101.INS*	XBRL Instance Document.
101.SCH*	XBRL Taxonomy Extension Schema.
101.CAL*	XBRL Taxonomy Extension Calculation Linkbase.
101.DEF*	XBRL Taxonomy Extension Definition Linkbase.
101.LAB*	XBRL Taxonomy Extension Label Linkbase.
101.PRE*	XBRL Taxonomy Extension Presentation Linkbase.

*	Filed herewith.
**	Furnished herewith.

17

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

		TRANSCONTINENTAL GAS PIPE LINE COMPANY, LLC (Registrant)
Dated:	July 30, 2015	By:	/s/ Jeffrey P. Heinrichs
			Jeffrey P. Heinrichs
			Controller (Principal Accounting Officer)

EXHIBIT INDEX

Exhibit Number	Description
2	Certificate of Conversion dated December 22, 2008 and effective December 31, 2008 (filed on February 24, 2011 as Exhibit 2.1 to our Form 10-K and incorporated herein by reference).
3.1	Certificate of Formation dated December 22, 2008 and effective December 31, 2008 (filed on February 24, 2011 as Exhibit 3.1 to our Form 10-K and incorporated herein by reference).
3.2	Amended and Restated Operating Agreement of Transcontinental Gas Pipe Line Company, LLC dated February 17, 2010 (filed on October 28, 2010 as Exhibit 3.2 to our Form 10-Q and incorporated herein by reference).
31.1*	Certification of Principal Executive Officer pursuant to Rules 13a-14(a) and 15d-14(a) promulgated under the Securities Exchange Act of 1934, as amended, and Item 601(b)(31) of Regulation S-K, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.
31.2*	Certification of Principal Financial Officer pursuant to Rules 13a-14(a) and 15d-14(a) promulgated under the Securities Exchange Act of 1934, as amended, and Item 601(b)(31) of Regulation S-K, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.
32**	Certification of Principal Executive Officer and Principal Financial Officer pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.
101.INS*	XBRL Instance Document.
101.SCH*	XBRL Taxonomy Extension Schema.
101.CAL*	XBRL Taxonomy Extension Calculation Linkbase.
101.DEF*	XBRL Taxonomy Extension Definition Linkbase.
101.LAB*	XBRL Taxonomy Extension Label Linkbase.
101.PRE*	XBRL Taxonomy Extension Presentation Linkbase.

*	Filed herewith.
**	Furnished herewith.

EX-31.1

Exhibit 31.1

SECTION 302 CERTIFICATION

I, Rory L. Miller, certify that:

1. I have reviewed this Quarterly Report on Form 10-Q of Transcontinental Gas Pipe Line Company, LLC;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: July 30, 2015

By:	/s/ Rory L. Miller
	Rory L. Miller
	Senior Vice President - Atlantic-Gulf
	(Principal Executive Officer)

EX-31.2

Exhibit 31.2

SECTION 302 CERTIFICATION

I, Ted T. Timmermans, certify that:

1. I have reviewed this Quarterly Report on Form 10-Q of Transcontinental Gas Pipe Line Company, LLC;

2. Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3. Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4. The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a) Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b) Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d) Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5. The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

(a) All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

(b) Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Date: July 30, 2015

By:	/s/ Ted T. Timmermans
	Ted T. Timmermans
	Vice President and Chief Accounting Officer
	(Principal Financial Officer)

EX-32

Exhibit 32

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350,

AS ADOPTED PURSUANT TO

SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of Transcontinental Gas Pipe Line Company, LLC (the “Company”) on Form 10-Q for the period ending June 30, 2015 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), each of the undersigned hereby certifies, in his capacity as an officer of the Company, pursuant to 18 U.S.C. §1350, as adopted pursuant to §906 of the Sarbanes-Oxley Act of 2002, that to his knowledge:

(1) The Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2) The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

/s/ Rory L. Miller

Rory L. Miller

Senior Vice President - Atlantic-Gulf

July 30, 2015

/s/ Ted T. Timmermans

Ted T. Timmermans

Vice President and Chief Accounting Officer

July 30, 2015

A signed original of this written statement required by Section 906 has been provided to, and will be retained by, the Company and furnished to the Securities and Exchange Commission or its staff upon request.

The foregoing certification is being furnished to the Securities and Exchange Commission as an exhibit to the Report and shall not be considered filed as part of the Report.

XML

ARO Trust (Notes)

6 Months Ended

Jun. 30, 2015

Investments, Debt and Equity Securities [Abstract]

ARO Trust

ARO TRUST

Available-for-Sale Investments

We are entitled to collect in rates the amounts necessary to fund our asset retirement obligations (ARO). We deposit monthly, into an external trust account (ARO Trust), the revenues specifically designated for ARO. The ARO Trust carries a moderate risk portfolio. We measure the financial instruments held in our ARO Trust at fair value. However, in accordance with the ASC Topic 980, Regulated Operations, both realized and unrealized gains and losses of the ARO Trust are recorded as regulatory assets or liabilities.

Effective March 1, 2013, the annual funding obligation is approximately $36.4 million, with deposits made monthly.

Investments in available-for-sale securities within the ARO Trust at fair value were as follows (in millions):

	June 30, 2015				December 31, 2014
	Amortized Cost Basis		Fair Value		Amortized Cost Basis		Fair Value
Cash and Money Market Funds	$	5.0	$	5.0	$	2.1	$	2.1
U.S. Equity Funds	18.0		22.2		15.0		19.0
International Equity Funds	11.7		12.2		8.0		8.2
Municipal Bond Funds	23.0		23.2		17.7		18.2
Total	$	57.7	$	62.6	$	42.8	$	47.5

XML

Debt and Financing Arrangements (Notes)

6 Months Ended

Jun. 30, 2015

Debt Disclosure [Abstract]

Debt and Financing Arrangements

DEBT AND FINANCING ARRANGEMENTS

Credit Facility

On February 2, 2015, the previous credit facility to which we were a party was terminated in connection with the merger of the former Williams Partners L.P. with and into ACMP. Simultaneously, we along with WPZ and Northwest Pipeline LLC (Northwest), as co-borrowers, entered into a new $3.5 billion credit facility. Total letter of credit capacity available to WPZ under the $3.5 billion credit facility is $1.125 billion. We may borrow up to $500 million under this credit facility to the extent not otherwise utilized by WPZ and Northwest. At June 30, 2015, no letters of credit have been issued and no loans are outstanding under our credit facility.

WPZ participates in a commercial paper program, and WPZ management considers amounts outstanding under this program to be a reduction of available capacity under the credit facility. The program allows a maximum outstanding amount at any time of $3 billion of unsecured commercial paper notes. At June 30, 2015, WPZ had approximately $1.7 billion of commercial paper outstanding.

Long-Term Debt Due Within One Year

The long-term debt due within one year at June 30, 2015 is associated with the $200 million of 6.4 percent notes that mature on April 15, 2016.

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Condensed Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Operating Revenues:
Natural gas sales	$ 36,327	$ 18,438	$ 57,734	$ 46,006
Natural gas transportation	319,356	283,979	641,916	584,360
Natural gas storage	34,322	34,665	69,467	71,260
Other	916	1,372	1,827	2,490
Total operating revenues	390,921	338,454	770,944	704,116
Operating Costs and Expenses:
Cost of natural gas sales	36,327	18,438	57,734	46,006
Cost of natural gas transportation	6,068	6,751	18,963	17,954
Operation and maintenance	63,225	63,905	131,508	124,338
Administrative and general	44,728	44,597	91,687	91,731
Depreciation and amortization	67,387	67,702	133,692	137,611
Taxes - other than income taxes	11,953	11,363	24,494	23,645
Other expense, net	14,171	5,955	31,986	13,406
Total operating costs and expenses	243,859	218,711	490,064	454,691
Operating Income	147,062	119,743	280,880	249,425
Other (Income) and Other Expenses:
Interest expense	20,656	21,197	41,463	43,156
Allowance for equity and borrowed funds used during construction (AFUDC)	(15,597)	(4,391)	(30,249)	(7,373)
Equity in earnings of unconsolidated affiliates	(1,234)	(1,380)	(2,753)	(2,857)
Miscellaneous other (income) expenses, net	440	(1,172)	804	(770)
Total other (income) and other expenses	4,265	14,254	9,265	32,156
Net Income	142,797	105,489	271,615	217,269
Other comprehensive income (loss):
Equity interest in unrealized gain (loss) on interest rate hedges (includes $83 and $86 for the three months ended and $167 and $170 for the six months ended June 30, 2015 and June 30, 2014, respectively, of accumulated other comprehensive income reclassification for equity interest in realized losses on interest rate hedges)	50	(41)	(3)	(3)
Comprehensive Income	$ 142,847	$ 105,448	$ 271,612	$ 217,266

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Basis of Presentation (Notes)

6 Months Ended

Jun. 30, 2015

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation

BASIS OF PRESENTATION

In this report, Transco (which includes Transcontinental Gas Pipe Line Company, LLC and, unless the context otherwise requires, all of our majority-owned subsidiaries) is at times referred to in the first person as “we,” “us” or “our.”

Transco is indirectly owned by Williams Partners L.P. (WPZ), a publicly traded Delaware limited partnership, which is consolidated by The Williams Companies, Inc. (Williams). On February 2, 2015, WPZ was merged into Access Midstream Partners, L.P. (ACMP), another publicly traded limited partnership consolidated by Williams. ACMP was the surviving partnership and was subsequently renamed Williams Partners, L.P. At June 30, 2015, Williams holds an approximate 60 percent interest in WPZ, comprised of an approximate 58 percent limited partner interest and all of the 2 percent general partner interest.

General

The condensed consolidated unaudited financial statements include our accounts and the accounts of the subsidiaries we control. Companies in which we and our subsidiaries own 20 percent to 50 percent of the voting common stock or otherwise exercise significant influence over operating and financial policies of the company are accounted for under the equity method. The equity method investments as of June 30, 2015 and December 31, 2014 consist of Cardinal Pipeline Company, LLC (Cardinal) with an ownership interest of approximately 45 percent and Pine Needle LNG Company, LLC (Pine Needle) with an ownership interest of 35 percent. We received distributions associated with our equity method investments totaling $3.2 million and $4.4 million in the six months ended June 30, 2015 and June 30, 2014, respectively. Included in the distributions are $0.9 million and $0.5 million return of capital in 2015 and 2014, respectively.

The condensed consolidated unaudited financial statements have been prepared from our books and records. Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (GAAP) have been condensed or omitted in this Form 10-Q pursuant to Securities and Exchange Commission rules and regulations. The condensed consolidated unaudited financial statements include all normal recurring adjustments and others which, in the opinion of our management, are necessary to present fairly our interim financial statements. These condensed consolidated unaudited financial statements should be read in conjunction with the consolidated financial statements and the notes thereto included in our 2014 Annual Report on Form 10-K.

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated unaudited financial statements and accompanying notes. Actual results could differ from those estimates.

Accounting Standards Issued But Not Yet Adopted

In July 2015, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2015-11 “Simplifying the Measurement of Inventory” (ASU 2015-11). ASU 2015-11 simplifies the guidance on the subsequent measurement of inventory, excluding inventory measured using last-in, first out or the retail inventory method. Under the new standard, in scope inventory should be measured at the lower of cost and net realizable value. The new standard is effective for interim and annual periods beginning after December 15, 2016, with early adoption permitted. We are evaluating the impact of the new standard.

In April 2015, the FASB issued ASU 2015-3 “Interest - Imputation of Interest: Simplifying the Presentation of Debt Issuance Costs” (ASU 2015-3). ASU 2015-3 simplifies the presentation of debt issuance costs by requiring such costs be presented as a deduction from the corresponding debt liability. The guidance is effective for financial statements issued for reporting periods beginning after December 15, 2015, and interim periods within the reporting periods and requires retrospective presentation. We are evaluating the impact of the new standard.

In February 2015, the FASB issued ASU 2015-2 “Amendments to the Consolidation Analysis” (ASU 2015-2). ASU 2015-2 alters the models used to determine consolidation conclusions for certain entities, including limited partnerships, and may require additional disclosures. The ASU is effective for financial statements issued for reporting periods beginning after December 15, 2015, and interim periods within the reporting periods with either retrospective or modified retrospective presentation allowed. We are currently evaluating the impact of the new standard on our consolidated financial statements.

In May 2014, the FASB issued ASU 2014-09 establishing Accounting Standards Codification Topic 606, “Revenue from Contracts with Customers” (ASC 606). ASC 606 establishes a comprehensive new revenue recognition model designed to depict the transfer of goods or services to a customer in an amount that reflects the consideration the entity expects to be entitled to receive in exchange for those goods or services and requires significantly enhanced revenue disclosures. The standard is effective for annual reporting periods beginning after December 15, 2017, and interim periods within the reporting period. ASC 606 allows either full retrospective or modified retrospective transition and early adoption is permitted for annual periods beginning after December 15, 2016. We continue to evaluate both the impact of this new standard on our consolidated financial statements and the transition method we will utilize for adoption.

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Other (Details) $ in Millions	6 Months Ended
	Jun. 30, 2014 USD ($)
Other Income and Expenses [Abstract]
Capitalization of project feasibility costs previously expensed	$ 3.5

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Contingent Liabilities and Commitments (Notes)

6 Months Ended

Jun. 30, 2015

Commitments and Contingencies Disclosure [Abstract]

Contingent Liabilities and Commitments

CONTINGENT LIABILITIES AND COMMITMENTS

Rate Matters

General rate case (Docket No. RP06-569) On August 31, 2006, we submitted to the Federal Energy Regulatory Commission (FERC) a general rate filing principally designed to recover increased costs. The rates became effective March 1, 2007, subject to refund and the outcome of a hearing. All issues in this proceeding except one have been resolved by settlement.

The one issue reserved for litigation or further settlement relates to our proposal to change the design of the rates for service under one of our storage rate schedules, which was implemented subject to refund on March 1, 2007. A hearing on that issue was held before a FERC Administrative Law Judge (ALJ) in July 2008. In November 2008, the ALJ issued an initial decision in which he determined that our proposed incremental rate design is unjust and unreasonable. On January 21, 2010, the FERC reversed the ALJ’s initial decision and approved our proposed incremental rate design. Certain parties sought rehearing of the FERC’s order and, on April 2, 2012, the FERC denied the rehearing request. On June 1, 2012, one of the parties filed an appeal in the U.S. Court of Appeals for the D.C. Circuit (D.C. Circuit). On February 21, 2014, the D.C. Circuit issued an opinion that vacated and remanded the FERC's order because the FERC did not adequately support its conclusions. On October 16, 2014, the FERC issued an order establishing a "paper hearing" and requesting briefs on certain questions raised by the D.C. Circuit's opinion. Parties to the proceeding filed initial and reply briefs on February 6, 2015 and March 6, 2015, respectively. We intend to continue to pursue approval of our proposed rate design. If we are unsuccessful, it is reasonably possible that refunds could be as much as $17 million at June 30, 2015.

Environmental Matters

We have had studies underway for many years to test some of our facilities for the presence of toxic and hazardous substances such as polychlorinated biphenyls (PCBs) and mercury to determine to what extent, if any, remediation may be necessary. We have also similarly evaluated past on-site disposal of hydrocarbons at a number of our facilities. We have worked closely with and responded to data requests from the U.S. Environmental Protection Agency (EPA) and state agencies regarding such potential contamination of certain of our sites. On the basis of the findings to date, we estimate that environmental assessment and remediation costs under various federal and state statutes will total approximately $4 million to $6 million (including both expense and capital expenditures), measured on an undiscounted basis, and will substantially be spent over the next three to four years. This estimate depends on a number of assumptions concerning the scope of remediation that will be required at certain locations and the cost of the remedial measures. We are conducting environmental assessments and implementing a variety of remedial measures that may result in increases or decreases in the total estimated costs. At June 30, 2015, we had a balance of approximately $1.8 million for the expense portion of these estimated costs recorded in current liabilities ($0.8 million) and other long-term liabilities ($1.0 million) in the accompanying Condensed Consolidated Balance Sheet. At December 31, 2014, we had a balance of approximately $2.7 million for the expense portion of these estimated costs recorded in current liabilities ($0.8 million) and other long-term liabilities ($1.9 million) in the accompanying Condensed Consolidated Balance Sheet.

We have been identified as a potentially responsible party (PRP) at various Superfund and state waste disposal sites. Based on present volumetric estimates and other factors, our estimated aggregate exposure for remediation of these sites is less than $0.5 million. The estimated remediation costs for all of these sites are included in the $4 million to $6 million range discussed above. Liability under the Comprehensive Environmental Response, Compensation and Liability Act and applicable state law can be joint and several with other PRPs. Although volumetric allocation is a factor in assessing liability, it is not necessarily determinative; thus, the ultimate liability could be substantially greater than the amounts described above.

In March 2008, the EPA promulgated a new, lower National Ambient Air Quality Standard (NAAQS) for ground-level ozone. In May 2012, the EPA completed designation of new eight-hour ozone non-attainment areas. Several facilities are located in 2008 ozone non-attainment areas. To date, no federal actions have been proposed to mandate additional emission controls at these facilities. Pursuant to recently proposed state regulatory actions associated with implementation of the 2008 ozone standard, we anticipate that some facilities may be subject to increased controls within five years. As a result, the cost of additions to property, plant, and equipment is expected to increase. We are unable at this time to estimate with any certainty the cost of additions that may be required to meet the proposed regulations.

In December 2014, the EPA proposed to further reduce the ground-level ozone NAAQS from the March 2008 levels; the EPA is anticipated to finalize any revisions in late 2015. Revisions to the ozone NAAQS will result in additional federal and state regulatory actions that may impact our operations. As a result, the cost of additions to property, plant and equipment is expected to increase. We are unable at this time to estimate with any certainty the cost of additions that may be required to meet new regulations.

On January 22, 2010, the EPA set a new one-hour nitrogen dioxide (NO2) NAAQS. The effective date of the new NO2 standard was April 12, 2010. On January 20, 2012, the EPA determined pursuant to available information that no area in the country is violating the 2010 NO2 NAAQS and thus designated all areas of the country as “unclassifiable/attainment.” Also, at that time, the EPA noted its plan to deploy an expanded NO2 monitoring network beginning in 2013. However, on October 5, 2012, the EPA proposed a graduated implementation of the monitoring network between January 1, 2014 and January 1, 2017. Once three years of data is collected from the new monitoring network, the EPA will reassess attainment status with the one-hour NO2 NAAQS. Until that time, the EPA or states may require ambient air quality modeling on a case by case basis to demonstrate compliance with the NO2 standard. Because we are unable to predict the outcome of the EPA’s or states’ future assessment using the new monitoring network, we are unable to estimate the cost of additions that may be required to meet this regulation.

We consider prudently incurred environmental assessment and remediation costs and the costs associated with compliance with environmental standards to be recoverable through rates. To date, we have been permitted recovery of environmental costs, and it is our intent to continue seeking recovery of such costs through future rate filings. As a result, as estimated costs of environmental assessment and remediation are incurred, they are recorded as regulatory assets in the Condensed Consolidated Balance Sheet until collected through rates. At June 30, 2015, we had a balance of approximately $1.1 million of uncollected environmental related regulatory assets recorded in current assets in the accompanying Condensed Consolidated Balance Sheet. At December 31, 2014, we had a balance of approximately $1.7 million of uncollected environmental related regulatory assets recorded in current assets ($1.2 million) and other assets ($0.5 million) in the accompanying Condensed Consolidated Balance Sheet.

Other Matters

Various other proceedings are pending against us and are considered incidental to our operations.

Summary

We estimate that for all matters for which we are able to reasonably estimate a range of loss, including those noted above and others that are not individually significant, our aggregate reasonably possible losses beyond amounts accrued for all of our contingent liabilities are immaterial to our expected future annual results of operations, liquidity and financial position. These calculations have been made without consideration of any potential recovery from third parties. We have disclosed all significant matters for which we are unable to reasonably estimate a range of possible loss.

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Condensed Consolidated Statement of Comprehensive Income (Unaudited) (Parentheticals) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Accumulated other comprehensive income reclassification for realized losses on interest rate hedges	$ 83	$ 86	$ 167	$ 170

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Debt and Financing Arrangements (Details) - USD ($)	Jun. 30, 2015	Feb. 02, 2015
Williams Partners L.P. [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		$ 3,500,000,000
Commercial paper, outstanding	$ 1,700,000,000
$3.5 billion credit facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	500,000,000
Letters of credit outstanding, amount	0
Line of credit facility, amount outstanding	0
$3.5 billion credit facility [Member] | Williams Partners L.P. [Member] | Commercial paper [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	3,000,000,000
$3.5 billion credit facility [Member] | Williams Partners L.P. [Member] | Letter of credit [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,125,000,000

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Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Jul. 30, 2015
Entity [Abstract]
Entity Registrant Name	Transcontinental Gas Pipe Line Company, LLC
Entity Central Index Key	0000099250
Document Type	10-Q
Document Period End Date	Jun. 30, 2015
Amendment Flag	false
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		0

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Debt and Financing Arrangements Long-term Debt Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Long-term debt due within one year	$ 200,000	$ 0
6.4 percent notes	6.40%
6.4% due 2016 [Member]
Debt Instrument [Line Items]
Long-term debt due within one year	$ 200,000

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Condensed Consolidated Balance Sheet (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Current Assets:
Cash	$ 0	$ 173
Receivables:
Affiliates	431	654
Advances to affiliate	187,980	306,910
Trade and other	149,689	130,735
Transportation and exchange gas receivables	9,578	3,485
Inventories	58,985	66,699
Regulatory assets	103,255	77,810
Other	19,691	14,683
Total current assets	529,609	601,149
Investments, at cost plus equity in undistributed earnings	46,562	47,050
Property, Plant and Equipment:
Natural gas transmission plant	10,275,813	9,645,382
Less-Accumulated depreciation and amortization	3,365,599	3,257,844
Total property, plant and equipment, net	6,910,214	6,387,538
Other Assets:
Regulatory assets	222,983	239,080
Other	80,830	75,066
Total other assets	303,813	314,146
Total Assets	7,790,198	7,349,883
Payables:
Affiliates	46,413	37,688
Trade and other	291,300	268,740
Transportation and exchange gas payables	3,832	4,701
Accrued liabilities	97,495	104,105
Long-term debt due within one year	200,000	0
Total current liabilities	639,040	415,234
Long-Term Debt	1,228,568	1,428,495
Other Long-Term Liabilities:
Asset retirement obligations	276,957	280,031
Regulatory liabilities	354,219	326,083
Other	76,490	35,728
Total other long-term liabilities	$ 707,666	$ 641,842
Contingent Liabilities and Commitments (Note 2)
Owner's Equity:
Member's capital	$ 2,836,499	$ 2,524,499
Retained earnings	2,378,543	2,339,928
Accumulated other comprehensive loss	(118)	(115)
Total owner's equity	5,214,924	4,864,312
Total liabilities and owner's equity	$ 7,790,198	$ 7,349,883

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Other (Notes)

6 Months Ended

Jun. 30, 2015

Other Income and Expenses [Abstract]

Other

OTHER

For the six months ended June 30, 2014, we capitalized $3.5 million of project feasibility cost associated with various projects, which had been expensed in prior periods in Other expense, net, upon determining that the projects were probable of development.

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Transactions with Affiliates (Notes)

6 Months Ended

Jun. 30, 2015

Related Party Transactions [Abstract]

Transactions with Affiliates

TRANSACTIONS WITH AFFILIATES

We are a participant in WPZ’s cash management program, and we make advances to and receive advances from WPZ. At June 30, 2015 and December 31, 2014, our advances to WPZ totaled approximately $188.0 million and $306.9 million, respectively. These advances are represented by demand notes and are classified as Current Assets in the accompanying Condensed Consolidated Balance Sheet. Advances are stated at the historical carrying amounts. Interest income is recognized when chargeable and collectability is reasonably assured. The interest rate on these intercompany demand notes is based upon the daily overnight investment rate paid on WPZ’s excess cash at the end of each month. At June 30, 2015, the interest rate was 0.01 percent.

Included in Operating Revenues in the accompanying Condensed Consolidated Statement of Comprehensive Income are revenues received from affiliates of $0.7 million and $1.9 million for the three and six months ended June 30, 2015, respectively, and $1.5 million and $2.8 million for the three and six months ended June 30, 2014, respectively. The rates charged to provide sales and services to affiliates are the same as those that are charged to similarly-situated nonaffiliated customers.

Included in Cost of natural gas sales in the accompanying Condensed Consolidated Statement of Comprehensive Income are cost of gas purchased from affiliates of $1.7 million and $4.2 million for the three and six months ended June 30, 2015, respectively and $3.4 million and $6.8 million for the three and six months ended June 30, 2014, respectively. All gas purchases are made at market or contract prices.

We have no employees. Services necessary to operate our business are provided to us by Williams and certain affiliates of Williams. We reimburse Williams and its affiliates for all direct and indirect expenses incurred or payments made (including salary, bonus, incentive compensation and benefits) in connection with these services. Employees of Williams also provide general, administrative and management services to us, and we are charged for certain administrative expenses incurred by Williams. These charges are either directly identifiable or allocated to our assets. Direct charges are for goods and services provided by Williams at our request. Allocated charges are based on a three-factor formula, which considers revenues; property, plant and equipment; and payroll. In management’s estimation, the allocation methodologies used are reasonable and result in a reasonable allocation to us of our costs of doing business incurred by Williams. We were billed $81.6 million and $162.6 million in the three and six months ended June 30, 2015, respectively, and $74.5 million and $149.7 million in the three and six months ended June 30, 2014, respectively, for these services. Such expenses are primarily included in Administrative and general and Operation and maintenance expenses in the accompanying Condensed Consolidated Statement of Comprehensive Income.

We provide services to certain of our affiliates. We recorded reductions in operating expenses for services provided to and reimbursed by our affiliates of $1.5 million and $2.7 million for the three and six months ended June 30, 2015, respectively, and $1.9 million and $3.2 million for the three and six months ended June 30, 2014, respectively. In the first quarter of 2014, pursuant to construction agreements, we received pre-payments from Williams Field Services Group, LLC of $4.2 million associated with capital projects.

We made equity distributions totaling $233.0 million and $235.0 million during the six months ended June 30, 2015 and 2014, respectively. During July 2015, we made an additional distribution of $141.0 million. Our parent made contributions to us totaling $312.0 million and $94.0 million in the six months ended June 30, 2015 and 2014, respectively, to fund a portion of our expenditures for additions to property, plant and equipment. In July 2015, our parent made an additional $179.0 million contribution to us.

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ARO Trust (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Annual funding obligation	$ 36.4
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost basis	57.7	$ 42.8
Available-for-sale securities, fair value	62.6	47.5
Cash and Money Market Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost basis	5.0	2.1
Available-for-sale securities, fair value	5.0	2.1
U.S. Equity Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost basis	18.0	15.0
Available-for-sale securities, fair value	22.2	19.0
International Equity Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost basis	11.7	8.0
Available-for-sale securities, fair value	12.2	8.2
Municipal Bond Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost basis	23.0	17.7
Available-for-sale securities, fair value	$ 23.2	$ 18.2

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Basis of Presentation (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Parent, total parent ownership percentage	60.00%
Parent, limited partner ownership percentage	58.00%
Parent, general partner ownership percentage	2.00%
Schedule of Equity Method Investments [Line Items]
Equity method investment, distributions	$ 3,200	$ 4,400
Equity method investment, return of capital	$ 902	$ 469
Cardinal Pipeline Company, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	45.00%		45.00%
Pine Needle LNG Company, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	35.00%		35.00%

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ARO Trust (Tables)

6 Months Ended

Jun. 30, 2015

Investments, Debt and Equity Securities [Abstract]

ARO Trust

Investments in available-for-sale securities within the ARO Trust at fair value were as follows (in millions):

	June 30, 2015				December 31, 2014
	Amortized Cost Basis		Fair Value		Amortized Cost Basis		Fair Value
Cash and Money Market Funds	$	5.0	$	5.0	$	2.1	$	2.1
U.S. Equity Funds	18.0		22.2		15.0		19.0
International Equity Funds	11.7		12.2		8.0		8.2
Municipal Bond Funds	23.0		23.2		17.7		18.2
Total	$	57.7	$	62.6	$	42.8	$	47.5

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Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2015

Fair Value Disclosures [Abstract]

Fair Value Measurements

The following table presents, by level within the fair value hierarchy, certain of our financial assets and liabilities. The carrying values of cash, short-term financial assets (advances to affiliate) that have variable interest rates, accounts receivable and accounts payable approximate fair value because of the short-term nature of these instruments. Therefore, these assets and liabilities are not presented in the following table.

							Fair Value Measurements Using
	Carrying Amount			Fair Value			Quoted Prices In Active Markets for Identical Assets (Level  1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)
	(Millions)
Assets (liabilities) at June 30, 2015:
Measured on a recurring basis:
ARO Trust investments	$	62.6		$	62.6		$	62.6	$	—		$	—
Additional disclosures:
Notes receivable	2.5			2.5			—		2.5			—
Long-term debt	(1,428.6		)	(1,546.7		)	—		(1,546.7		)	—
Assets (liabilities) at December 31, 2014:
Measured on a recurring basis:
ARO Trust investments	$	47.5		$	47.5		$	47.5	$	—		$	—
Additional disclosures:
Notes receivable	3.8			3.8			—		3.8			—
Long-term debt	(1,428.5		)	(1,506.4		)	—		(1,506.4		)	—

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Contingent Liabilities and Commitments (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Potential refund obligation	$ 17,000
Site Contingency [Line Items]
Regulatory assets, current	103,255	$ 77,810
Regulatory assets, noncurrent	222,983	239,080
Environmental assessment and remediation [Member]
Site Contingency [Line Items]
Environmental assessment and remediation costs, low estimate	4,000
Environmental assessment and remediation costs, high estimate	6,000
Accrued environmental assessment and remediation costs, total	1,800	2,700
Accrued environmental assessment and remediation costs, current	800	800
Accrued environmental assessment and remediation costs, noncurrent	1,000	1,900
Regulatory assets, total	1,100	1,700
Regulatory assets, current	1,100	1,200
Regulatory assets, noncurrent	$ 0	$ 500
Environmental assessment and remediation [Member] | Minimum [Member]
Site Contingency [Line Items]
Expected duration of environmental assessment and remediation spending	3 years
Environmental assessment and remediation [Member] | Maximum [Member]
Site Contingency [Line Items]
Expected duration of environmental assessment and remediation spending	4 years
Potentially responsible party at various Superfund and state waste disposal sites [Member]
Site Contingency [Line Items]
Environmental assessment and remediation costs, high estimate	$ 500

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Transactions with Affiliates (Details) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Jul. 30, 2015 USD ($)	Jun. 30, 2015 USD ($) employee	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) employee	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)	Mar. 31, 2014 USD ($)
Related Party Transaction [Line Items]
Advances to affiliate		$ 187,980		$ 187,980		$ 306,910
Related party transaction, rate				0.01%
Operating revenues, related party		700	$ 1,500	$ 1,900	$ 2,800
Cost of natural gas sales, related party		$ 1,700	3,400	$ 4,200	6,800
Entity number of employees | employee		0		0
Expenses, related party		$ 81,600	74,500	$ 162,600	149,700
Cash distributions to parent				233,000	235,000
Cash contributions from parent				312,000	94,000
Affiliated Entity [Member]
Related Party Transaction [Line Items]
Expenses, related party		(1,500)	$ (1,900)	(2,700)	$ (3,200)
Williams Partners L.P. [Member]
Related Party Transaction [Line Items]
Advances to affiliate		$ 188,000		$ 188,000		$ 306,900
Williams Field Services Group, LLC [Member]
Related Party Transaction [Line Items]
Pre-payments for capital projects							$ 4,200
Subsequent Event [Member]
Related Party Transaction [Line Items]
Cash distributions to parent	$ 141,000
Cash contributions from parent	$ 179,000

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Condensed Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Cash flows from operating activities:
Net income	$ 271,615	$ 217,269
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	133,692	137,153
Allowance for equity funds used during construction (equity AFUDC)	(23,123)	(5,469)
Changes in operating assets and liabilities:
Receivables - affiliates	223	1,808
Receivables - trade and other	(18,954)	37,509
Transportation and exchange gas receivable	(6,093)	2,506
Inventories	7,714	(26,632)
Payables - affiliates	8,725	15,596
Payables - trade	9,319	(103,555)
Accrued liabilities	(9,048)	(10,567)
Reserve for rate refunds	0	20,075
Asset retirement obligation removal costs	(972)	(7,555)
Other, net	13,482	(4,602)
Net cash provided by operating activities	386,580	273,536
Cash flows from financing activities:
Cash distributions to parent	(233,000)	(235,000)
Cash contributions from parent	312,000	94,000
Other, net	13,539	6,830
Net cash provided by (used in) financing activities	92,539	(134,170)
Cash flows from investing activities:
Property, plant and equipment additions, net of equity AFUDC	(633,476)	(219,971)
Contributions and advances for construction costs	32,600	23,801
Disposal of property, plant and equipment, net	620	2,958
Advances to affiliate, net	118,930	59,578
Return of capital from unconsolidated affiliates	902	469
Purchase of ARO Trust investments	(42,022)	(35,012)
Proceeds from sale of ARO Trust investments	27,075	27,411
Proceeds from insurance	14,804	0
Other, net	1,275	1,414
Net cash used in investing activities	(479,292)	(139,352)
Increase (decrease) in cash	(173)	14
Cash at beginning of period	173	113
Cash at end of period	0	127
Increase to property, plant and equipment, net of equity AFUDC	(630,346)	(253,298)
Changes in related accounts payable and accrued liabilities	(3,130)	33,327
Property, plant and equipment additions, net of equity AFUDC	$ (633,476)	$ (219,971)

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Fair Value Measurements (Notes)

6 Months Ended

Jun. 30, 2015

Fair Value Disclosures [Abstract]

Fair Value Measurements

FAIR VALUE MEASUREMENTS

The following table presents, by level within the fair value hierarchy, certain of our financial assets and liabilities. The carrying values of cash, short-term financial assets (advances to affiliate) that have variable interest rates, accounts receivable and accounts payable approximate fair value because of the short-term nature of these instruments. Therefore, these assets and liabilities are not presented in the following table.

							Fair Value Measurements Using
	Carrying Amount			Fair Value			Quoted Prices In Active Markets for Identical Assets (Level  1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)
	(Millions)
Assets (liabilities) at June 30, 2015:
Measured on a recurring basis:
ARO Trust investments	$	62.6		$	62.6		$	62.6	$	—		$	—
Additional disclosures:
Notes receivable	2.5			2.5			—		2.5			—
Long-term debt	(1,428.6		)	(1,546.7		)	—		(1,546.7		)	—
Assets (liabilities) at December 31, 2014:
Measured on a recurring basis:
ARO Trust investments	$	47.5		$	47.5		$	47.5	$	—		$	—
Additional disclosures:
Notes receivable	3.8			3.8			—		3.8			—
Long-term debt	(1,428.5		)	(1,506.4		)	—		(1,506.4		)	—

Fair Value of Methods

The following methods and assumptions were used to estimate the fair value of each class of financial instruments for which it is practicable to estimate that value:

ARO Trust investments — We deposit a portion of our collected rates, pursuant to the terms of the Docket No. RP12-993 rate case settlement, into the ARO Trust, which is specifically designated to fund future asset retirement obligations. The ARO Trust invests in a portfolio of actively traded mutual funds that are measured at fair value on a recurring basis based on quoted prices in an active market, are classified as available-for-sale and are reported in Other Assets-Other in the Condensed Consolidated Balance Sheet. However, both realized and unrealized gains and losses are ultimately recorded as regulatory assets or liabilities. See Note 4 for more information regarding the ARO Trust.

Notes receivable — The disclosed fair value of our notes receivable is determined by an income approach, which considers the underlying contract amounts and our assessment of our ability to recover these amounts. The current portion is reported in Trade and other receivables, and the noncurrent portion is reported in Other Assets-Other in the Condensed Consolidated Balance Sheet.

Long-term debt — The disclosed fair value of our long-term debt is determined by a market approach using broker quoted indicative period-end bond prices. The quoted prices are based on observable transactions in less active markets for our debt or similar instruments.

Reclassifications of fair value between Level 1, Level 2, and Level 3 of the fair value hierarchy, if applicable, are made at the end of each quarter. No transfers between Level 1 and Level 2 occurred during the six months ended June 30, 2015 or 2014.

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Fair Value Measurements (Details) - USD ($)	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
ARO Trust investments	$ 62,600,000	$ 47,500,000
Fair Value, Transfers Between Level 1 and Level 2, Description and Policy [Abstract]
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount	0		$ 0
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount	0		0
Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount	0		0
Fair Value, Liabilities, Level 2 to Level 1 Transfers, Amount	0		$ 0
Fair Value, Inputs, Level 1 [Member]
Additional Fair Value Elements [Abstract]
Notes receivable, Fair Value Disclosure	0	0
Long-term debt, Fair Value	0	0
Fair Value, Inputs, Level 2 [Member]
Additional Fair Value Elements [Abstract]
Notes receivable, Fair Value Disclosure	2,500,000	3,800,000
Long-term debt, Fair Value	(1,546,700,000)	(1,506,400,000)
Fair Value, Inputs, Level 3 [Member]
Additional Fair Value Elements [Abstract]
Notes receivable, Fair Value Disclosure	0	0
Long-term debt, Fair Value	0	0
Reported Value Measurement [Member]
Additional Fair Value Elements [Abstract]
Notes receivable, Fair Value Disclosure	2,500,000	3,800,000
Long-term debt, Fair Value	(1,428,600,000)	(1,428,500,000)
Estimate of Fair Value Measurement [Member]
Additional Fair Value Elements [Abstract]
Notes receivable, Fair Value Disclosure	2,500,000	3,800,000
Long-term debt, Fair Value	(1,546,700,000)	(1,506,400,000)
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
ARO Trust investments	62,600,000	47,500,000
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
ARO Trust investments	0	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
ARO Trust investments	0	0
Fair Value, Measurements, Recurring [Member] | Reported Value Measurement [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
ARO Trust investments	62,600,000	47,500,000
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value Measurement [Member]
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]
ARO Trust investments	$ 62,600,000	$ 47,500,000