Consolidated Statements of Income (Unaudited) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Revenues, net		$ 210,112	$ 189,057	$ 417,085	$ 372,090
Cost of revenues	[1]	139,649	123,734	277,750	242,806
Gross profit	[1]	70,463	65,323	139,335	129,284
Operating expenses:
General and administrative expenses		27,640	24,425	56,906	48,462
Selling and marketing expenses		15,151	13,095	29,103	26,435
Depreciation and amortization		10,582	9,535	21,086	18,907
Total operating expenses		53,373	47,055	107,095	93,804
Income from operations		17,090	18,268	32,240	35,480
Foreign exchange gain, net		1,414	886	2,029	1,268
Interest expense		(706)	(465)	(1,244)	(897)
Other income, net		2,232	2,512	5,766	5,698
Income before income tax expense		20,030	21,201	38,791	41,549
Income tax expense		5,510	823	1,057	4,383
Loss from equity-method investment		58	0	114	0
Net income attributable to ExlService Holdings, Inc. stockholders		$ 14,462	$ 20,378	$ 37,620	$ 37,166
Earnings per share attributable to ExlService Holdings, Inc. stockholders:
Basic (in dollars per share)		$ 0.42	$ 0.60	$ 1.09	$ 1.10
Diluted (in dollars per share)		$ 0.41	$ 0.58	$ 1.07	$ 1.06
Weighted-average number of shares used in computing earnings per share attributable to ExlService Holdings, Inc. stockholders:
Basic (in shares)		34,511,777	33,819,320	34,479,202	33,833,153
Diluted (in shares)		35,142,388	34,993,226	35,222,838	35,051,767

[1] Exclusive of depreciation and amortization.