CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating Activities:
Net income	$ 175.6	$ 226.3
Adjustments to reconcile net income to cash provided by operations:
Depreciation and amortization	268.4	258.5
Amortization of deferred costs and other	10.5	7.2
Loss (gain) on sale of assets and impairments	0.9	(0.8)
Changes in operating assets and liabilities:
Trade and other receivables	25.7	40.2
Gas receivables and storage assets	(18.6)	(22.3)
Other assets	(5.5)	11.3
Trade and other payables	(7.7)	(3.2)
Gas payables	10.9	(0.2)
Accrued liabilities	33.6	21.3
Other liabilities	7.4	(2.5)
Net cash provided by operating activities	501.2	535.8
Investing Activities:
Capital expenditures	(350.5)	(276.0)
Proceeds from sale of operating assets	3.7	2.3
Advances to affiliates	(4.3)	(3.1)
Net cash used in investing activities	(351.1)	(276.8)
Financing Activities:
Proceeds from long-term debt, net of issuance cost	495.0	495.2
Repayment of borrowings from long-term debt	0.0	(350.0)
Proceeds from borrowings on revolving credit agreement	432.9	475.0
Repayment of borrowings on revolving credit agreement	(727.9)	(795.0)
Principal payment of finance lease obligation	(0.5)	(0.5)
Advances from affiliates	(4.1)	3.1
Distributions paid	0.0	(76.7)
Net cash provided by (used in) financing activities	195.4	(248.9)
Increase in cash and cash equivalents	345.5	10.1
Cash and cash equivalents at beginning of period	3.7	3.6
Cash and cash equivalents at end of period	$ 349.2	$ 13.7