Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Assets:
Total assets	$ 83,504	$ 97,366
Liabilities:
Total liabilities	48,362	5,520
Cash and Cash Equivalents [Member]
Assets:
Total assets	82,398
Marketable securities [Member]
Assets:
Total assets	1,106	97,366
Acquisition Consideration [Member]
Liabilities:
Total liabilities	48,362
Derivative Liability [Member]
Liabilities:
Total liabilities		5,520
Quoted Prices in Active Markets (Level 1) [Member]
Assets:
Total assets	83,504	97,366
Liabilities:
Total liabilities	0	0
Quoted Prices in Active Markets (Level 1) [Member] | Cash and Cash Equivalents [Member]
Assets:
Total assets	82,398
Quoted Prices in Active Markets (Level 1) [Member] | Marketable securities [Member]
Assets:
Total assets	831	97,366
Quoted Prices in Active Markets (Level 1) [Member] | Derivative Liability [Member]
Liabilities:
Total liabilities		0
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 Other Observable Inputs (Level 2) [Member] | Derivative Liability [Member]
Liabilities:
Total liabilities		0
Significant Unobservable Inputs (Level 3) [Member]
Assets:
Total assets		0
Liabilities:
Total liabilities	48,362	5,520
Significant Unobservable Inputs (Level 3) [Member] | Marketable securities [Member]
Assets:
Total assets	275	0
Significant Unobservable Inputs (Level 3) [Member] | Acquisition Consideration [Member]
Liabilities:
Total liabilities	$ 48,362
Significant Unobservable Inputs (Level 3) [Member] | Derivative Liability [Member]
Liabilities:
Total liabilities		$ 5,520