CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Comprehensive (loss) income:
Net (loss) income	$ (45.9)	$ 44.3	$ (77.9)	$ 99.4
Other comprehensive income (loss) before income tax effect:
Net income (loss) on foreign currency cash flow hedges reclassified as income	0.0	0.0	(0.1)	(0.1)
Defined benefit plans and other postretirement benefits:
OPEB curtailment gain, net	0.0	(8.0)	0.0	(8.0)
Amortization of prior service benefit (cost) during the period	0.0	(0.3)	0.1	(1.2)
Amortization of net loss during the period	1.7	1.1	5.0	3.6
Other comprehensive income (loss) before income tax effect	1.7	(7.2)	5.0	(5.7)
Income tax effect	0.0	(0.1)	0.0	(0.2)
Other comprehensive income (loss)	1.7	(7.3)	5.0	(5.9)
Comprehensive (loss) income	(44.2)	37.0	(72.9)	93.5
Comprehensive loss attributable to noncontrolling interests	(3.9)	0.0	(4.8)	0.0
Comprehensive (loss) income attributable to Century stockholders	$ (40.3)	$ 37.0	$ (68.1)	$ 93.5