Contract payment term description.

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- Definition

Contracts payment term.

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No definition available.

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- Definition

Summary of significant accounting policies.

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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No definition available.

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- Definition

The amount of deposits held by branches of foreign institutions.

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- Definition

Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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- Definition

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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Number of reporting units tested for impairment of goodwill. A reporting unit is an operating segment or one level below an operating segment.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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No definition available.

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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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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended								12 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) Segment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Contract payment term description									contracts typically contain billing terms that provide for invoicing monthly or upon completion of milestones, and payment on a net 30-day basis.
Contracts payment, term									30 days
Number of reportable segments \| Segment									1
Goodwill, impaired, accumulated impairment loss	$ 0								$ 0
Goodwill, impairment loss									$ 0
Performance based share awards, performance period									3 years
Number of operating segments \| Segment									1
Revenue	396,636,000	$ 373,918,000	$ 366,717,000	$ 341,254,000	$ 377,910,000	$ 332,968,000	$ 324,315,000	$ 302,780,000	$ 1,478,525,000	$ 1,337,973,000	$ 1,229,162,000
Foreign financial institutions, actual deposits	$ 7,100,000				$ 11,900,000				7,100,000	11,900,000
Federal Government Agencies And Departments
Summary Of Significant Accounting Policies [Line Items]
Revenue									$ 561,000,000.0	$ 546,100,000	$ 550,200,000
Federal Government Agencies And Departments \| Customer Concentration Risk \| Sales Revenue, Net
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage									38.00%	41.00%	45.00%
International Clients \| Geographic Concentration Risk \| Sales Revenue, Net
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage									8.00%	13.00%	9.00%
International \| Long-Lived Assets
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage									17.00%	12.00%
Minimum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful life									2 years
Finite-lived intangible asset, useful life									1 year
Minimum \| Other Assets
Summary Of Significant Accounting Policies [Line Items]
Finite-lived intangible asset, useful life									3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful life									7 years
Finite-lived intangible asset, useful life									10 years
Maximum \| Other Assets
Summary Of Significant Accounting Policies [Line Items]
Finite-lived intangible asset, useful life									5 years