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		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Contingent Consideration Liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 53,900	$ 53,600	$ 52,800	$ 51,000
Changes in fair value	10,500	200	11,600	2,800
Ending Balance	64,400	53,800	64,400	53,800
Common Stock Warrant Liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	69	692	809	6,196
Changes in fair value	380	356	(360)	(5,148)
Ending Balance	$ 449	$ 1,048	$ 449	$ 1,048