Benefit Plans (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Retirement Benefits [Abstract]
Service cost	$ 0.8	$ 0.7
Interest cost	0.7	2.7
Expected return on plan assets	(0.2)	(1.7)
Net periodic benefit cost	$ 1.3	$ 1.7