Segments (Reconciliation of Net Income (Loss) to EBITDA) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Net income (loss)	$ 72.5	$ (37.4)	$ (15.3)
Interest and debt expense, net	(177.4)	(132.1)	(133.6)
(Gain) loss on modification/extinguishment of debt	0.0	7.5	(0.1)
(Provision) benefit for income taxes	1.9	0.2	0.4
Depreciation, amortization and accretion	328.9	244.2	237.4
EBITDA	580.7	346.6	356.0
CMLP
Segment Reporting Information [Line Items]
Net income (loss)	(52.2)	(44.0)	(23.4)
Interest and debt expense, net	(177.4)	(132.1)	(133.6)
(Gain) loss on modification/extinguishment of debt	0.0	7.5	(0.1)
(Provision) benefit for income taxes	1.7	0.1	(0.1)
Depreciation, amortization and accretion	334.6	258.4	251.5
EBITDA	$ 461.5	$ 354.1	$ 361.5