Income Taxes - Component of Income Taxes Expenses (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Currently payable (refundable):
U.S. federal and state	$ 27.5	$ 7.6	$ 7.4
Non-U.S.	9.5	3.3	15.2
Total	37.0	10.9	22.6
Deferred income taxes (benefit):
U.S. federal and state	(33.7)	(58.5)	3.8
Non-U.S.	2.7	144.9	6.1
Total	(31.0)	86.4	9.9
Provision for income taxes (benefit)	$ 6.0	$ 97.3	$ 32.5