Revenue Recognition - Deferred Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Revenue Recognition
Revenue recognized during the period that was included in deferred revenues at the beginning of the period	$ 3,455
Deferred revenue, current portion	51,840	$ 56,016
Deferred revenue, Long-term	25,152	23,808
Total deferred revenues	$ 76,992	$ 79,824