Summary of Income Tax Expense (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred income tax expense (benefit):
Total deferred income tax benefit	$ (3.9)	$ (2.1)	$ (5.1)
Total income tax benefit	(0.6)	(9.1)	(8.4)
Continuing Operations
Current income tax expense (benefit):
Federal	(1.5)	(13.9)	(3.1)
State	0.2	0.4	(0.7)
Foreign	3.2	6.5
Total current income tax expense (benefit)	1.9	(7.0)	(3.8)
Deferred income tax expense (benefit):
Federal	(1.6)	1.3	(4.6)
State	0.2	(0.1)
Foreign	(1.1)	(3.3)
Total deferred income tax benefit	(2.5)	(2.1)	(4.6)
Total income tax benefit	$ (0.6)	$ (9.1)	$ (8.4)