Summary of Potentially Dilutive Common Stock Equivalents (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Average unamortized share-based compensation expense:
Exercise prices on common stock options, lower range	$ 3	$ 3	$ 3
Exercise prices on common stock options, upper range	10	10	10
Weighted average exercise price of the Warrants	$ 5.64	$ 5.73	$ 6.66
Restricted Stock
Average unamortized share-based compensation expense:
Average unamortized share-based compensation expense	$ 2.5	$ 1.3	$ 0.6
Common Stock Option Awards
Average unamortized share-based compensation expense:
Average unamortized share-based compensation expense	0.0	0.0	0.1
Restricted Stock Unit Awards
Average unamortized share-based compensation expense:
Average unamortized share-based compensation expense	$ 1.4	$ 1.0	$ 0.0