Long-Term Debt - Interest Expense Associated with Convertible Notes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Debt Disclosure [Abstract]
Contractual coupon rate of interest	$ 2,338	$ 2,338	$ 2,338
Accretion of Convertible Notes discount and amortization of deferred financing costs	4,426	4,048	3,760
Interest expense for the convertible notes	$ 6,764	$ 6,386	$ 6,098