Increase in percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

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- Definition

Debt Instrument, Incremental Decrease in Basis Spread on Variable Rate Resulting from Upgrades

+ References

No definition available.

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- Definition

Debt Instrument, Incremental Increase in Basis Spread on Variable Rate Resulting from Downgrades

+ References

No definition available.

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- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM format.

+ References

No definition available.

+ Details

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12317-112629

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
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-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

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-Publisher FASB
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-Topic 470
-SubTopic 50
-Section 40
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12355-112629

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- Definition

Amount of cash outflow for cost from early extinguishment and prepayment of debt. Includes, but is not limited to, third-party cost, premium paid, and other fee paid to lender directly for debt extinguishment or debt prepayment. Excludes accrued interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

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- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

No definition available.

+ Details

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- Definition

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

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- Definition

The cash outflow for a borrowing having initial term of repayment within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

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- Definition

Carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Debt (Senior Notes - Narrative) (Details) - USD ($) $ in Millions	1 Months Ended				3 Months Ended		6 Months Ended	12 Months Ended
	Oct. 31, 2017	Sep. 30, 2017	Jul. 31, 2016	Jan. 31, 2015	Mar. 31, 2018	Mar. 31, 2017	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Loss on extinguishment of debt		$ 59				$ 1	$ 11
Payment of premiums		53
Senior Notes [Member]
Debt Instrument [Line Items]
Proceeds from issuance of debt		1,100		$ 2,200
Increase in basis spread			1.75%
Senior Notes [Member] \| Over LIBOR [Member]
Debt Instrument [Line Items]
Incremental increase in basis points resulting from downgrades				0.25%
Incremental decrease in basis points resulting from upgrades				0.25%
Increase in basis spread			1.75%
3.30% Senior Notes due January 2018 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior notes				$ 350
Stated interest rate				3.30%
Maturity date, year and month				2018-01
Repayments of long-term debt							$ 38
4.05% Senior Notes due January 2020 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior notes				$ 850
Stated interest rate			5.80%	4.05%	4.05%			4.05%
Maturity date, year and month				2020-01	2020-01			2020-01
Repayments of long-term debt		758
4.95% Senior Notes due January 2025 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior notes				$ 1,000
Stated interest rate			6.70%	4.95%	4.95%			4.95%
Maturity date, year and month				2025-01	2025-01			2025-01
7.50% Senior Notes due February 2018 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Stated interest rate							7.50%
Maturity date, year and month							2018-02
Repayments of long-term debt							$ 212
7.15% Senior Notes due June 2018 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Stated interest rate							7.15%
Maturity date, year and month							2018-06
Repayments of long-term debt							$ 26
7.50% Senior Notes due April 2026 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior notes		$ 650
Stated interest rate		7.50%			7.50%			7.50%
Maturity date, year and month		2026-04			2026-04			2026-04
2015 Term Loan due December 2020 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Repayments of long-term debt		$ 327
7.75% Senior Notes due October 2027 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Senior notes		$ 500
Stated interest rate		7.75%			7.75%			7.75%
Maturity date, year and month		2027-10			2027-10			2027-10
4.10% Senior Notes due March 2022 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Stated interest rate					4.10%			4.10%
Maturity date, year and month					2022-03			2022-03
2017 Senior Notes [Member] \| Short-term Debt [Member]
Debt Instrument [Line Items]
Repayment of short-term debt	$ 40
Maximum [Member] \| 4.05% Senior Notes due January 2020 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Stated interest rate									6.05%
Maximum [Member] \| 4.95% Senior Notes due January 2025 [Member] \| Long-term Debt [Member]
Debt Instrument [Line Items]
Stated interest rate									6.95%