CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating Activities:
Net income	$ 125.2	$ 117.5
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization	93.2	91.0
Amortization of deferred costs and other	0.3	2.5
Gain on sale of assets	0.0	(0.1)
Changes in operating assets and liabilities:
Trade and other receivables	6.0	7.4
Gas transportation receivables and storage assets	2.2	(13.2)
Other assets	4.8	(0.7)
Trade and other payables	0.9	12.4
Other payables, affiliates	(0.2)	0.0
Gas transportation payables	(5.0)	(1.6)
Accrued liabilities	(30.7)	(29.3)
Regulatory assets and liabilities	(1.8)	(3.4)
Other liabilities	6.2	5.4
Net cash provided by operating activities	201.1	187.9
Investing Activities:
Capital expenditures	(60.1)	(52.9)
Proceeds from sale of operating assets	0.7	0.2
Advances to affiliates	(2.7)	0.0
Net cash used in investing activities	(62.1)	(52.7)
Financing Activities:
Proceeds from long-term debt, net of issuance cost	495.0	0.0
Repayment of borrowings from long-term debt	300.0	0.0
Proceeds from borrowings on revolving credit facility	0.0	110.0
Repayment of borrowings on revolving credit facility	0.0	(230.0)
Principal payment of finance lease obligation	(0.2)	(0.2)
Advances from affiliates	2.7	(0.1)
Net cash provided by (used in) financing activities	197.5	(120.3)
Increase in cash and cash equivalents	336.5	14.9
Cash and cash equivalents at beginning of period	39.1	2.9
Cash and cash equivalents at end of period	$ 375.6	$ 17.8