Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 31.4	$ 38.7
Other comprehensive income:
Amortization of net actuarial losses and prior service costs (credits), net of income taxes of $3.3 million, and $2.2 million	10.2	7.0
Comprehensive income	$ 41.6	$ 45.7