Interim Financial Statements (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Unbilled receivables	$ 142,700		$ 146,800
Contract liabilities	53,300		51,600
Deferred revenue and customer advances	34,896		$ 30,269
Revenue recognized	$ 8,100	$ 5,300