Transactions with Affiliates (Notes)	3 Months Ended
Mar. 31, 2019
Related Party Transactions [Abstract]
Transactions with Affiliates	TRANSACTIONS WITH AFFILIATES We are a participant in Williams' cash management program, and we receive advances from and make advances to Williams. At March 31, 2019, our advances from Williams totaled approximately $86.6 million and is classified as Payables - Advances from affiliates in the accompanying Condensed Consolidated Balance Sheet. At December 31, 2018, our advances to Williams totaled approximately $33.0 million and is classified as Receivables - Advances to affiliate in the accompanying Condensed Consolidated Balance Sheet. Advances are stated at the historical carrying amounts. Interest income and expense are 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 Williams' excess cash at the end of each month. At March 31, 2019, the interest rate was 2.33 percent. Included in Operating Revenues in the accompanying Condensed Consolidated Statement of Comprehensive Income are revenues received from affiliates of $3.3 million and $1.8 million for the three months ended March 31, 2019 and 2018, 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 $1.6 million and $1.9 million for the three months ended March 31, 2019 and 2018, 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 $92.2 million and $91.5 million in the three months ended March 31, 2019 and 2018, 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 $1.0 million for the three months ended March 31, 2019 and 2018, respectively. We made equity distributions totaling $176.0 million and $55.0 million during the three months ended March 31, 2019 and 2018, respectively. During April 2019, we made an additional distribution of $170.0 million. Our parent made contributions to us totaling $340.0 million in the three months ended March 31, 2018, to fund a portion of our expenditures for additions to property, plant and equipment.

TRANSACTIONS WITH AFFILIATES

We are a participant in Williams' cash management program, and we receive advances from and make advances to Williams. At March 31, 2019, our advances from Williams totaled approximately $86.6 million and is classified as Payables - Advances from affiliates in the accompanying Condensed Consolidated Balance Sheet. At December 31, 2018, our advances to Williams totaled approximately $33.0 million and is classified as Receivables - Advances to affiliate in the accompanying Condensed Consolidated Balance Sheet. Advances are stated at the historical carrying amounts. Interest income and expense are 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 Williams' excess cash at the end of each month. At March 31, 2019, the interest rate was 2.33 percent.

Included in Operating Revenues in the accompanying Condensed Consolidated Statement of Comprehensive Income are revenues received from affiliates of $3.3 million and $1.8 million for the three months ended March 31, 2019 and 2018, 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 $1.6 million and $1.9 million for the three months ended March 31, 2019 and 2018, 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 $92.2 million and $91.5 million in the three months ended March 31, 2019 and 2018, 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 $1.0 million for the three months ended March 31, 2019 and 2018, respectively.

We made equity distributions totaling $176.0 million and $55.0 million during the three months ended March 31, 2019 and 2018, respectively. During April 2019, we made an additional distribution of $170.0 million. Our parent made contributions to us totaling $340.0 million in the three months ended March 31, 2018, to fund a portion of our expenditures for additions to property, plant and equipment.