CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Operating Activities:
Net income	$ 119.0	$ 125.2
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization	99.8	93.2
Amortization of deferred costs and other	7.9	0.3
Changes in operating assets and liabilities:
Trade and other receivables	15.5	6.0
Gas transportation receivables and storage assets	56.8	2.2
Prepayments and other assets	10.3	4.8
Trade and other payables	(5.2)	0.9
Other payables, affiliates	0.1	(0.2)
Gas transportation payables	(34.6)	(5.0)
Accrued liabilities	(37.6)	(30.7)
Regulatory assets and liabilities	(34.1)	(1.8)
Other liabilities	8.1	6.2
Net cash provided by operating activities	206.0	201.1
Investing Activities:
Capital expenditures	(86.1)	(60.1)
Proceeds from sale of operating assets	0.1	0.7
Advances to affiliates	0.0	(2.7)
Net cash used in investing activities	(86.0)	(62.1)
Financing Activities:
Proceeds from long-term debt, net of issuance cost	0.0	495.0
Repayment of borrowings from long-term debt	0.0	(300.0)
Principal payment of finance lease obligation	(0.2)	(0.2)
Advances from affiliates	0.1	2.7
Net cash (used in) provided by financing activities	(0.1)	197.5
Increase in cash and cash equivalents	119.9	336.5
Cash and cash equivalents at beginning of period	215.6	39.1
Cash and cash equivalents at end of period	$ 335.5	$ 375.6