Contract Receivables, Net - Summary of Contract Receivables, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Receivables [Abstract]
Billed and billable	$ 274,237	$ 236,250
Allowance for doubtful accounts	(4,869)	(5,284)
Contract receivables, net	$ 269,368	$ 230,966

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant