Fair Value Measurements - Reconciliation of Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Details) - Level 3 - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Contingent consideration liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 70,500	$ 74,400	$ 78,200	$ 76,900
Change in fair value	400	5,700	2,700	3,200
Settlements	0	0	(10,000)	0
Balance at end of period	70,900	80,100	70,900	80,100
Common stock warrant liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	501	543	343	512
Change in fair value	(399)	64	(241)	95
Balance at end of period	$ 102	$ 607	$ 102	$ 607