General - Contingent Consideration (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2017
Fair value measurement of contingent consideration
Estimated undiscounted future contingent payments	$ 9,900				$ 9,900
Fair value of short-term contingent consideration	6,892				6,892
Fair value of long-term contingent consideration	2,158				$ 1,925
Liability for contingent consideration
Balance as of beginning of period	8,817
Changes in fair value	233	$ (100)
Balance as of end of period	$ 9,050
Forecast
Fair value measurement of contingent consideration
Estimated undiscounted future contingent payments			$ 2,700	$ 7,200