Derivatives and Hedge Accounting - Location of Gain or Loss Recognized (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Cost of revenues	[1]	$ 690,934	$ 623,936	$ 655,490
General and administrative expenses		142,040	113,891	126,909
Selling and marketing expenses		84,306	60,123	71,842
Depreciation and amortization expense		49,132	50,462	51,981
Income before income tax expense and earnings from equity affiliates		146,561	115,329	83,100
Income tax benefit/(expense) relating to above		(31,850)	(25,626)	(15,172)
Net income attributable to ExlService Holdings, Inc. stockholders		114,758	89,476	67,659
Foreign exchange gain, net		4,313	4,432	3,752
Gain/ (loss) on foreign currency exchange contracts | Derivatives Designated as Hedging Instruments | Derivatives in cash flow hedging relationships | Foreign currency exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Cost of revenues		7,785	1,008	3,269
General and administrative expenses		948	(161)	424
Selling and marketing expenses		53	(5)	46
Depreciation and amortization expense		478	(41)	212
Income before income tax expense and earnings from equity affiliates		9,264	801	3,951
Income tax benefit/(expense) relating to above		(1,530)	500	(1,173)
Net income attributable to ExlService Holdings, Inc. stockholders		7,734	1,301	2,778
Gain/ (loss) on foreign currency exchange contracts | Derivative not designated as hedging instruments | Fair value hedge | Foreign currency exchange contracts
Derivative Instruments, Gain (Loss) [Line Items]
Foreign exchange gain, net		$ 196	$ 3,686	$ 3,208

[1] Exclusive of depreciation and amortization expense.