Revenue - Activity of Deferred Contract Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Capitalized Contract Cost [Roll Forward]
Beginning balance	$ 72,265	$ 59,434
Capitalization of contract acquisition costs	38,756	40,172
Amortization of deferred contract acquisition costs	(32,145)	(27,341)
Ending balance	$ 78,876	$ 72,265