Revenue from Contracts with Customers Revenue by Customer (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Revenue from External Customer [Line Items]
Revenue	$ 633,224	$ 610,912
U.S. Government
Revenue from External Customer [Line Items]
Revenue	628,498	600,528
State agencies, international agencies and commercial entities
Revenue from External Customer [Line Items]
Revenue	$ 4,726	$ 10,384

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).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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+ Details