Summary of Significant Accounting Policies - Reconciliation of Liabilities Measured at Fair Value Using Significant Observable Inputs (Level 3) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Embedded Derivative Liabilities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Exercises		$ 0
Significant Unobservable Inputs (Level 3) [Member] | Contingent Purchase Consideration [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 53,000	0
Purchases/additions	0	53,000
Changes in fair value	(2,000)
Ending Balance	51,000	53,000
Significant Unobservable Inputs (Level 3) [Member] | Common Stock Warrant Liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	5,093	31,341
Purchases/additions	0
Exercises	0	(916)
Changes in fair value	1,103	(25,332)
Ending Balance	6,196	5,093
Significant Unobservable Inputs (Level 3) [Member] | Embedded Derivative Liabilities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	0	233
Purchases/additions	0
Derecognition of liability		247
Sales/dispositions	0
Changes in fair value	0	14
Ending Balance	0	0
Significant Unobservable Inputs (Level 3) [Member] | Short-term Investments [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	0	0
Purchases/additions	11,926
Sales/dispositions	6,180
Changes in fair value	(5,746)
Ending Balance	$ 0	$ 0