Consolidated Statements of Income - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenues, net		$ 991,346	$ 883,112	$ 762,310
Cost of revenues	[1]	655,490	584,855	495,142
Gross profit	[1]	335,856	298,257	267,168
Operating expenses:
General and administrative expenses		126,909	116,202	102,515
Selling and marketing expenses		71,842	63,612	53,379
Depreciation and amortization expense		51,981	48,566	38,549
Impairment and restructuring charges		8,671	20,056	0
Total operating expenses		259,403	248,436	194,443
Income from operations		76,453	49,821	72,725
Foreign exchange gain, net		3,752	4,787	2,839
Interest expense		(13,612)	(7,227)	(1,889)
Other income, net		16,507	12,989	11,359
Income before income tax expense and earnings from equity affiliates		83,100	60,370	85,034
Income tax expense		15,172	3,397	36,146
Income before earnings from equity affiliates		67,928	56,973	48,888
Loss from equity-method investment		269	247	0
Net income attributable to ExlService Holdings, Inc. stockholders		$ 67,659	$ 56,726	$ 48,888
Earnings per share attributable to ExlService Holdings, Inc. stockholders:
Basic (in dollars per share)		$ 1.97	$ 1.65	$ 1.44
Diluted (in dollars per share)		$ 1.95	$ 1.62	$ 1.39
Weighted-average number of shares used in computing earnings per share:
Basic (in shares)		34,350,150	34,451,008	33,897,916
Diluted (in shares)		34,732,683	35,030,984	35,110,210

[1] Exclusive of depreciation and amortization expense.