Fair Value Measurements - Contingent Consideration Liabilities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($)
Contingent consideration liabilities measured at fair value
Balance at beginning of period	$ 13,779
Balance at end of period	12,485
Fair value | Level 3
Contingent consideration liabilities measured at fair value
Balance at beginning of period	13,779
Fair value adjustments included in operating expenses	(1,294)
Balance at end of period	$ 12,485