Business Acquisitions - Summary of Assets Acquired and Liabilities Assumed - Questar Acquisition (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Business Acquisition [Line Items]
Goodwill	$ 1,773,671	$ 1,781,332
Questar Pipelines
Business Acquisition [Line Items]
Gas plant, net	1,047,400	1,047,400
Other property and investments	51,300	51,300
Cash and cash equivalents	17,600	17,600
Accounts receivable	29,500	26,600
Prepaid expenses	27,400	27,400
Deferred charges and other assets	31,100	31,100
Goodwill	977,500	986,200
Deferred income taxes	14,100	15,400
Total assets acquired	2,195,900	2,203,000
Long-term debt	449,700	449,700
Trade and other payables	7,000	7,000
Deferred purchased gas costs	5,700	5,700
Customer deposits	3,200	3,200
Accrued general taxes	400	400
Accrued interest	4,700	4,700
Other current liabilities	14,500	14,500
Accumulated removal costs	56,600	56,600
Other deferred credits	85,600	85,600
Total liabilities assumed and noncontrolling interest	627,400	627,400
Net assets acquired	1,568,500	$ 1,575,600
Measurement Period Adjustments, Accounts receivable	2,900
Measurement Period Adjustments, Goodwill	(8,700)
Measurement Period Adjustments, Deferred income taxes	(1,300)
Measurement Period Adjustments, Total assets	(7,100)
Measurement Period Adjustments, Net assets acquired	$ (7,100)