Revenue Recognition - Activity of Deferred Contract Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Capitalized Contract Cost [Roll Forward]
Beginning balance	$ 70,742	$ 59,811	$ 72,265	$ 59,434
Capitalization of contract acquisition costs	8,892	8,608	15,013	15,234
Amortization of deferred contract acquisition costs	(7,866)	(6,553)	(15,510)	(12,802)
Ending balance	$ 71,768	$ 61,866	$ 71,768	$ 61,866