PROPERTY AND EQUIPMENT, NET (Components of Property and Equipment and Depreciation) (Details) - USD ($) $ in Thousands			12 Months Ended
	Nov. 17, 2021	Nov. 01, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment, gross			$ 402,862	$ 297,314
Less accumulated depreciation and amortization			(166,648)	(127,781)
Total			236,214	169,533	$ 165,259
Depreciation and amortization expense			65,500	50,500	35,400
Payments to acquire an office building			$ 111,501	68,793	99,308
Computer hardware
Property, Plant and Equipment [Line Items]
Weighted average useful life (in years)			3 years
Property and equipment, gross			$ 167,546	117,333
Buildings
Property, Plant and Equipment [Line Items]
Weighted average useful life (in years)			44 years
Property and equipment, gross			$ 55,388	52,007
Leasehold improvements
Property, Plant and Equipment [Line Items]
Weighted average useful life (in years)			8 years
Property and equipment, gross			$ 37,828	39,675
Purchased computer software
Property, Plant and Equipment [Line Items]
Weighted average useful life (in years)			3 years
Property and equipment, gross			$ 33,649	31,993
Furniture, fixture and other equipment
Property, Plant and Equipment [Line Items]
Weighted average useful life (in years)			7 years
Property and equipment, gross			$ 31,961	31,859
Office equipment
Property, Plant and Equipment [Line Items]
Weighted average useful life (in years)			7 years
Property and equipment, gross			$ 22,881	20,971
Land improvements
Property, Plant and Equipment [Line Items]
Weighted average useful life (in years)			18 years
Property and equipment, gross			$ 2,137	2,137
Land
Property, Plant and Equipment [Line Items]
Property and equipment, gross			1,339	1,339
Construction in progress
Property, Plant and Equipment [Line Items]
Property and equipment, gross			50,133	0
Belarus
Property, Plant and Equipment [Line Items]
Total			75,422	73,988	75,984
Ukraine
Property, Plant and Equipment [Line Items]
Total			78,289	30,980	$ 24,652
Ukraine | Construction in progress
Property, Plant and Equipment [Line Items]
Payments to acquire an office building	$ 50,100
Minsk, Belarus | Buildings
Property, Plant and Equipment [Line Items]
Payments to acquire an office building		$ 18,900
Leased building, before accumulated depreciation			3,300	6,700
Leased building, accumulated depreciation			200	200
Depreciation expense			$ 100	$ 200