Schedule of Activity Related to Redeemable Preferred Stock (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Debt Disclosure [Abstract]
Balance, December 31, 2015			$ 21.9
Dividends on Redeemable Preferred Stock, in-kind	$ 0.5	$ 0.5	1.4	$ 1.0
Accretion of fair value adjustment to Redeemable Preferred Stock	0.2	$ 0.2	0.8	$ 0.6
Balance, September 30, 2016	$ 24.1		$ 24.1