Fair Value Measurements - Reconciliation of Liabilities Measured at Fair Value Using Significant Unobservable Inputs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Change in fair value of contingent consideration	$ 1,800	$ 400	$ 6,100	$ 2,700
Contingent consideration liabilities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	53,100	70,500	63,800	78,200
Change in fair value	1,800	400	6,100	2,700
Settlements	0	0	(15,000)	(10,000)
Balance at end of period	$ 54,900	$ 70,900	$ 54,900	$ 70,900