Transactions with Affiliates (Notes)	6 Months Ended
Jun. 30, 2018
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, 2018 and December 31, 2017, our advances to WPZ totaled approximately $589.1 million and $395.2 million, respectively. These advances are represented by demand notes and are classified as Receivables - Advances to affiliate 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, 2018, the interest rate was 1.80 percent. Included in Operating Revenues in the accompanying Condensed Consolidated Statement of Comprehensive Income are revenues received from affiliates of $1.5 million and $3.3 million for the three and six months ended June 30, 2018, respectively, and $3.1 million and $6.4 million for the three and six months ended June 30, 2017, 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 $1.8 million and $3.7 million for the three and six months ended June 30, 2018, respectively, and $0.8 million and $1.9 million for the three and six months ended June 30, 2017, 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 $99.3 million and $190.8 million in the three and six months ended June 30, 2018, respectively, and $87.3 million and $169.7 million in the three and six months ended June 30, 2017, respectively, for these services. Such expenses are primarily included in Operation and maintenance and Administrative and general 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 $1.2 million and $2.2 million for the three and six months ended June 30, 2018, respectively, and $0.9 million and $1.8 million for the three and six months ended June 30, 2017, respectively. We made equity distributions totaling $190.0 million and $210.0 million during the six months ended June 30, 2018 and 2017, respectively. During July 2018, we made an additional distribution of $100.0 million. Our parent made contributions to us totaling $340.0 million and $110.0 million in the six months ended June 30, 2018 and 2017, respectively, to fund a portion of our expenditures for additions to property, plant and equipment. During July 2017, we recorded deferred revenue and recognized a non-cash distribution to our parent of $240 million associated with funds received by WPZ related to the March 2016 WPZ agreement with the member-sponsors of Sabal Trail regarding the Hillabee Expansion and Sabal Trail projects. Although the agreement was between WPZ and the member-sponsors, since the agreement was, in part, related to furthering the completion of Hillabee, this deferred revenue is assigned to our results of operations over the 25-year term of the capacity agreement with Sabal Trail.

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, 2018 and December 31, 2017, our advances to WPZ totaled approximately $589.1 million and $395.2 million, respectively. These advances are represented by demand notes and are classified as Receivables - Advances to affiliate 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, 2018, the interest rate was 1.80 percent.

Included in Operating Revenues in the accompanying Condensed Consolidated Statement of Comprehensive Income are revenues received from affiliates of $1.5 million and $3.3 million for the three and six months ended June 30, 2018, respectively, and $3.1 million and $6.4 million for the three and six months ended June 30, 2017, 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 $1.8 million and $3.7 million for the three and six months ended June 30, 2018, respectively, and $0.8 million and $1.9 million for the three and six months ended June 30, 2017, 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 $99.3 million and $190.8 million in the three and six months ended June 30, 2018, respectively, and $87.3 million and $169.7 million in the three and six months ended June 30, 2017, respectively, for these services. Such expenses are primarily included in Operation and maintenance and Administrative and general 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 $1.2 million and $2.2 million for the three and six months ended June 30, 2018, respectively, and $0.9 million and $1.8 million for the three and six months ended June 30, 2017, respectively.

We made equity distributions totaling $190.0 million and $210.0 million during the six months ended June 30, 2018 and 2017, respectively. During July 2018, we made an additional distribution of $100.0 million. Our parent made contributions to us totaling $340.0 million and $110.0 million in the six months ended June 30, 2018 and 2017, respectively, to fund a portion of our expenditures for additions to property, plant and equipment.

During July 2017, we recorded deferred revenue and recognized a non-cash distribution to our parent of $240 million associated with funds received by WPZ related to the March 2016 WPZ agreement with the member-sponsors of Sabal Trail regarding the Hillabee Expansion and Sabal Trail projects. Although the agreement was between WPZ and the member-sponsors, since the agreement was, in part, related to furthering the completion of Hillabee, this deferred revenue is assigned to our results of operations over the 25-year term of the capacity agreement with Sabal Trail.