UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Net income (loss)	$ 99.9	$ 14.6	$ 94.7	$ (96.2)
Other comprehensive income:
Defined benefit pension and retiree health benefit plans	0.1	0.1	0.2	0.2
Total other comprehensive income	0.1	0.1	0.2	0.2
Comprehensive income (loss) attributable to partners' capital (deficit)	100.0	14.7	94.9	(96.0)
Less: Comprehensive loss attributable to noncontrolling interest	(3.1)	(1.1)	(18.5)	(1.1)
Comprehensive income (loss) attributable to partners' capital (deficit)	$ 103.1	$ 15.8	$ 113.4	$ (94.9)