Revenue Recognition - Accounts Receivable and Deferred Revenue (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Assets
Accounts receivable	$ 58,706	$ 53,351
Liabilities:
Deferred revenue, current portion	52,392	56,016
Deferred revenue, long-term portion	22,533	23,808
Total deferred revenues	74,925	79,824
Current accounts receivable	58,706	53,351
Other noncurrent assets	12,357	$ 12,476
BGI
Liabilities:
Deferred revenue, current portion	$ 500
Accounts receivable			$ 2,500