Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets
Accrued compensation benefits	$ 14,416	$ 8,204
Reserves	5,171	4,670
Net operating loss and credit carryover	4,877	3,202
Foreign tax credit carryover	35,981	35,629
Tax reserve benefit	5,409	3,916
Interest carryover	2,080	16,438
Operating lease liability	43,280	39,283
Other	4,722	4,846
Total deferred tax assets	115,936	116,188
Valuation allowance	(12,050)	(13,784)
Net deferred tax assets	103,886	102,404
Deferred tax liabilities
Depreciation	(4,087)	(4,384)
Prepaid expenses	(3,341)	(1,779)
Unbilled receivables	(2,178)	(22,958)
Intangible assets	(54,908)	(31,480)
Operating lease right-of-use assets	(43,034)	(37,540)
Investment in unconsolidated foreign subsidiary	(727)	(1,051)
Total deferred tax liabilities	(108,275)	(99,192)
Deferred Tax Liabilities, Net	$ (4,389)
Net deferred tax assets (liabilities)		$ 3,212