Fair Value Measurements - Contingent Consideration Liability (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Payments of contingent consideration	$ (4,634)	$ (4,856)	$ (3,104)
Change in fair value of contingent consideration	1,866	(3,298)	9,672
Contingent Consideration
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value measurement, beginning of period	15,800	17,358	8,634
Issuance	0	0	21,500
Payments of contingent consideration			(3,104)
Change in fair value of contingent consideration	(1,866)	3,298	(9,672)
Fair value measurement, end of period	$ 9,300	$ 15,800	$ 17,358