Revenue from Contracts with Customers - Contract Asset and Liability Balances (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Change in Contract Asset Balance
Beginning of period balance	$ 4,306	$ 4,578
Commission costs and upfront payments to a customer capitalized in period	1,106	1,165
Amortization of contract assets	(809)	(811)
End of period balance	4,603	4,932
Change In Contract With Customer, Liability [Roll Forward]
Beginning of period balance	12,529	10,498
Revenue deferred in period	3,801	3,520
Revenue recognized from amounts included in contract liabilities	(2,674)	(1,916)
End of period balance	$ 13,656	$ 12,102