Transactions with Major Customers and Affiliates (Notes)	1 Months Ended
	Feb. 28, 2021
Transactions with Major Customers and Affiliates [Abstract]
Transactions with Major Customers and Affiliates	Transactions with Major Customers and Affiliates Major Customers Dominion Energy, Inc. accounted for $297.7 million (11 percent), $248.5 million (10 percent) and $250.7 million (10 percent) of our operating revenues during the years ended December 31, 2021, 2020, and 2019, respectively. No other customers accounted for 10 percent or more of our revenues during any of the three years ended December 31, 2021. Affiliates We are a participant in Williams’ cash management program, and we make advances to and receive advances from Williams. At December 31, 2021 and 2020, our advances to Williams totaled approximately $1,669.4 million and $642.7 million, respectively. These advances are represented by demand notes and are classified as Receivables - Advances to affiliate in the accompanying Consolidated Balance Sheet. Advances are stated at the historical carrying amounts. Interest expense and income are recognized when earned 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 December 31, 2021, the interest rate was 0.01 percent. Included in Operating Revenues in the accompanying Consolidated Statement of Comprehensive Income for 2021, 2020 and 2019 are revenues received from affiliates of $37.4 million, $11.4 million, and $10.5 million, 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 Consolidated Statement of Comprehensive Income for 2021, 2020 and 2019 are costs of gas purchased from affiliates of $7.9 million, $5.6 million, and $4.0 million, 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. In the accompanying Statement of Comprehensive Income, we have recorded approximately $329.7 million, $278.8 million, and $304.5 million during 2021, 2020 and 2019, respectively, for these service expenses, which are primarily included in Operation and maintenance and Administrative and general expenses. We provide services to certain of our affiliates. We recorded reductions in operating expenses for services provided to and reimbursed by our affiliates of $7.3 million, $5.1 million, and $4.4 million in 2021, 2020 and 2019, respectively. We made cash distributions to our parent of $343.7 million, $1,020.0 million and $824.0 million during 2021, 2020 and 2019, respectively. During January 2022, we made an additional cash distribution of $57.5 million. During 2021 and 2020, our parent made cash contributions totaling $417.0 million and $115.0 million, respectively, to us. During January 2022, our parent made an additional $128.0 million contribution to us. During 2019, we recognized a non-cash distribution of $25 million to our parent related to a settlement agreement between Williams and a co-owner in our Atlantic Sunrise project. Although the agreement was between Williams and a third party, since the agreement was in part related to our Atlantic Sunrise project, the settlement amount was added to our Atlantic Sunrise project financing obligation. Effective December 31, 2019, we made a $36.6 million non-cash distribution to our parent of our interests in our wholly-owned subsidiaries, Cardinal Operating Company, LLC, Pine Needle Operating Company, LLC, TransCarolina LNG Company, LLC, and TransCardinal Company, LLC.