Revenue Recognition - Accounts Receivable and Deferred Revenue (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets
Accounts receivable	$ 70,674	$ 53,351
Liabilities:
Deferred revenue, current portion	51,227	56,016
Deferred revenue, long-term portion	23,128	23,808
Total deferred revenues	74,355	79,824
Current accounts receivable	70,674	53,351
Other noncurrent assets	$ 12,156	$ 12,476