Summary of Significant Accounting Policies - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	May 16, 2014	Dec. 31, 2013
Liabilities
Expected volatility rate period	180 days
Maximum [Member]
Liabilities
Volatility rate	40.00%
Embedded Derivative Liabilities [Member]
Liabilities
Liabilities measured at fair value on a recurring basis	233	$ 247
Fair Value, Measurements, Recurring [Member] | Common Stock Warrant Liabilities [Member]
Liabilities
Liabilities measured at fair value on a recurring basis	5,093		31,341
Fair Value, Measurements, Recurring [Member] | Contingent Purchase Consideration [Member]
Liabilities
Liabilities measured at fair value on a recurring basis	53,000
Fair Value, Measurements, Recurring [Member] | Embedded Derivative Liabilities [Member]
Liabilities
Liabilities measured at fair value on a recurring basis			233
Fair Value, Measurements, Recurring [Member] | Money market fund shares [Member]
Assets
Assets measured at fair value on a recurring basis	8,021		69,120
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Common Stock Warrant Liabilities [Member]
Liabilities
Liabilities measured at fair value on a recurring basis	0		0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Contingent Purchase Consideration [Member]
Liabilities
Liabilities measured at fair value on a recurring basis	0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Embedded Derivative Liabilities [Member]
Liabilities
Liabilities measured at fair value on a recurring basis			0
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Money market fund shares [Member]
Assets
Assets measured at fair value on a recurring basis	8,021		69,120
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Common Stock Warrant Liabilities [Member]
Liabilities
Liabilities measured at fair value on a recurring basis	0		0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Contingent Purchase Consideration [Member]
Liabilities
Liabilities measured at fair value on a recurring basis	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Embedded Derivative Liabilities [Member]
Liabilities
Liabilities measured at fair value on a recurring basis			0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Money market fund shares [Member]
Assets
Assets measured at fair value on a recurring basis	0		0
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Common Stock Warrant Liabilities [Member]
Liabilities
Liabilities measured at fair value on a recurring basis	5,093		31,341
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Contingent Purchase Consideration [Member]
Liabilities
Liabilities measured at fair value on a recurring basis	53,000
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Embedded Derivative Liabilities [Member]
Liabilities
Liabilities measured at fair value on a recurring basis			233
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member] | Money market fund shares [Member]
Assets
Assets measured at fair value on a recurring basis	0		$ 0