Revenue Recognition - Accounts Receivable and Deferred Revenue (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Assets
Accounts receivable	$ 87,562	$ 78,565
Liabilities:
Deferred revenue, current portion	9,069	50,125
Deferred revenue, long-term portion	23,816	22,805
Total deferred revenues	$ 32,885	$ 72,930