Summary of Significant Accounting Policies - Rollforward of Unbilled Accounts Receivable (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Beginning Balance	$ 33,450	$ 37,227
Recognized during the period	248,574	252,445
Reclassified to receivables	(244,574)	(255,983)
Other	335	(239)
Ending Balance	$ 37,785	$ 33,450