Convertible Senior Notes - Components of Total Interest Expense, Net Recognized (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Debt Disclosure [Abstract]
Contractual coupon interest expense	$ 3,300	$ 3,300
Amortization of debt issuance costs	662	599	$ 101
Accretion of debt discount	5,250	4,818	$ 43
Total	$ 9,212	$ 8,717
Effective interest rate	8.66%	8.66%