Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net income (loss)	$ 12.6	$ (260.4)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Impairments	0.0	353.0
Depreciation and amortization	151.0	162.8
Utility credits	(40.4)	0.0
Deferred income tax (benefit) expense	1.3	(34.0)
Non-cash unit-based compensation	6.5	8.8
Non-cash (gain) loss on derivatives recognized in net income (loss)	7.8	(18.0)
Gain on extinguishment of debt	0.0	(5.3)
Amortization of debt issue costs, net discount (premium) of notes	1.2	1.0
Distribution of earnings from unconsolidated affiliates	0.0	1.6
(Income) loss from unconsolidated affiliates	6.3	(1.7)
Other operating activities	1.4	(1.2)
Changes in assets and liabilities:
Accounts receivable, accrued revenue, and other	(18.7)	124.8
Natural gas and NGLs inventory, prepaid expenses, and other	1.2	44.5
Accounts payable, accrued product purchases, and other accrued liabilities	95.6	(193.9)
Net cash provided by operating activities	225.8	182.0
Cash flows from investing activities:
Additions to property and equipment	(23.5)	(112.0)
Distribution from unconsolidated affiliates in excess of earnings	3.6	0.2
Other investing activities	0.7	(3.7)
Net cash used in investing activities	(19.2)	(115.5)
Cash flows from financing activities:
Proceeds from borrowings	200.0	440.0
Payments on borrowings	(300.0)	(241.0)
Conversion of restricted units, net of units withheld for taxes	(1.2)	(4.0)
Distribution to members	(47.1)	(93.3)
Distributions to non-controlling interests	(26.0)	(24.7)
Contributions by non-controlling interests	0.9	37.1
Other financing activities	0.0	0.1
Net cash provided by (used in) financing activities	(173.4)	114.2
Net increase in cash and cash equivalents	33.2	180.7
Cash and cash equivalents, beginning of period	39.6	77.4
Cash and cash equivalents, end of period	72.8	258.1
Supplemental disclosures of cash flow information:
Cash paid for interest	17.2	22.3
Non-cash investing activities:
Non-cash accrual of property and equipment	(2.7)	2.8
Right-of-use assets obtained in exchange for operating lease liabilities	10.2	4.8
Non-cash financing activities:
Fair value adjustment related to redeemable non-controlling interest	$ 0.0	$ (4.0)