Schedule of Activity Related to Redeemable Preferred Stock (Detail) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Debt Disclosure [Abstract]
Balance, December 31, 2015	$ 24.9	$ 21.9	$ 21.9
Dividends on Redeemable Preferred Stock, in-kind	0.0	0.5	2.0
Accretion of fair value adjustment to Redeemable Preferred Stock	0.2	$ 0.2	1.0
Balance, December 31, 2016	$ 25.1		$ 24.9