Summary of Significant Accounting Policies - Rollforward of Unbilled Accounts Receivable (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Beginning Balance	$ 37,227	$ 33,104
Recognized during the period	252,445	237,134
Reclassified to receivables	(255,983)	(231,689)
Other	(239)	(1,322)
Ending Balance	$ 33,450	$ 37,227