Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 27.8	$ 27.8
Other comprehensive (loss) income:
Amortization of net actuarial (gains) losses and prior service costs, net of income taxes of $0.1 million and $1.8 million	(0.6)	5.2
Comprehensive income	$ 27.2	$ 33.0