Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Assets:
Total assets	$ 46,183	$ 97,366
Liabilities:
Total liabilities	0	5,520
Marketable securities [Member]
Assets:
Total assets	46,183	97,366
Quoted Prices in Active Markets (Level 1) [Member]
Assets:
Total assets	46,183	97,366
Liabilities:
Total liabilities	0	0
Quoted Prices in Active Markets (Level 1) [Member] | Marketable securities [Member]
Assets:
Total assets	46,183	97,366
Significant Other Observable Inputs (Level 2) [Member]
Assets:
Total assets	0	0
Liabilities:
Total liabilities	0	0
Significant Other Observable Inputs (Level 2) [Member] | Marketable securities [Member]
Assets:
Total assets	0	0
Significant Unobservable Inputs (Level 3) [Member]
Assets:
Total assets	0	0
Liabilities:
Total liabilities	0	5,520
Significant Unobservable Inputs (Level 3) [Member] | Marketable securities [Member]
Assets:
Total assets	0	0
Derivative Liability [Member]
Liabilities:
Total liabilities	0	5,520
Derivative Liability [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Liabilities:
Total liabilities	0	0
Derivative Liability [Member] | Significant Other Observable Inputs (Level 2) [Member]
Liabilities:
Total liabilities	0	0
Derivative Liability [Member] | Significant Unobservable Inputs (Level 3) [Member]
Liabilities:
Total liabilities	$ 0	$ 5,520