Revenue Recognition - Changes in Contract Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue From Contract With Customer [Abstract]
Deferred revenue, Balance at Beginning of Period	$ 3,543	$ 2,617	$ 3,933	$ 2,837
Deferred revenue, Billings	1,173	1,736	2,608	2,884
Deferred revenue, Revenue Recognized	(1,769)	(1,392)	(3,594)	(2,760)
Deferred revenue, Balance at End of Period	$ 2,947	$ 2,961	$ 2,947	$ 2,961