Disclosure about a restatement of previous periods' segment information resulting from a change in the composition of the entity's reportable segments.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Segment Information - Additional Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) segment	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments \| segment	2
Revenues	$ 970,993	$ 904,405
Property and equipment, net	124,600		$ 122,751
United States
Segment Reporting Information [Line Items]
Revenues	735,800	$ 669,200
Property and equipment, net	$ 112,500		$ 109,900
Federal Solutions
Segment Reporting Information [Line Items]
Changes in reportable segments, description	we realigned the five business lines within our Federal Solutions segment into four business lines.
Critical Infrastructure
Segment Reporting Information [Line Items]
Changes in reportable segments, description	We re-aligned our Critical Infrastructure segment from three markets to two markets.