Fair Value Measurements - Reconciliation of Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Details) - Significant Unobservable Inputs (Level 3) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Contingent consideration	$ 53,900		$ 53,900		$ 52,800
Contingent Consideration Liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	53,400	$ 52,300	52,800	$ 51,000
Changes in fair value	500	1,300	1,100	2,600
Ending Balance	53,900	53,600	53,900	53,600
Common Stock Warrant Liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	222	1,669		6,196
Changes in fair value	(153)	(977)	(740)	(5,504)
Ending Balance	$ 69	$ 692	$ 69	$ 692