Summary of Potentially Dilutive Common Stock Equivalents (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Average unamortized share-based compensation expense:
Exercise prices on common stock options, lower range	$ 3.00	$ 3.00	$ 3.00	$ 3.00
Exercise prices on common stock options, upper range	10.00	10.00	10.00	10.00
Weighted average exercise price of the Warrants	$ 5.64	$ 5.64	$ 5.64	$ 5.75
Restricted Common Stock Awards
Average unamortized share-based compensation expense:
Average unamortized share-based compensation expense	$ 2.5	$ 1.4	$ 2.6	$ 1.3
Performance Share Awards
Average unamortized share-based compensation expense:
Average unamortized share-based compensation expense	$ 1.3	$ 1.8	$ 1.8	$ 0.8