Summary of Significant Accounting Policies - Rollforward of Deferred Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Beginning Balance	$ (57,763)	$ (47,611)
Revenue recognized that was included in deferred revenue at the beginning of the period	39,352	38,832
Consideration received in advance of services performed net of revenue recognized in the current period	(44,051)	(50,861)
Other	(1,184)	1,877
Ending Balance	$ (63,646)	$ (57,763)