Revenue from Contracts with Customers Revenue by Contract Type (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Revenue by Contract Type [Line Items]
Revenue	$ 675,545	$ 633,224
Cost-reimbursable
Revenue by Contract Type [Line Items]
Revenue	465,977	419,775
Time-and-materials
Revenue by Contract Type [Line Items]
Revenue	115,744	81,241
Fixed-price
Revenue by Contract Type [Line Items]
Revenue	$ 93,824	$ 132,208

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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+ Details