Revenue Recognition - Changes in Balance of Deferred Revenues (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($)
Revenue Recognition
Balance	$ 79,824
Increase in deferred revenues	1,579
Reclasses from deferred revenues to other short-term liabilities	(801)
Revenue recognized during the period that was included in deferred revenues at the beginning of the period	(5,290)
Revenue recognized from performance obligations satisfied within the same period	(957)
Balance	$ 74,355