Earnings Per Share - Computation of Basic and Diluted Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerators:
Net income	$ 8,429	$ 12,564	$ 30,840	$ 27,259
Denominators:
Basic weighted average common shares outstanding (in shares)	34,486,202	34,451,671	34,443,884	34,413,455
Dilutive effect of share based awards (in shares)	111,486	250,876	215,262	354,748
Diluted weighted average common shares outstanding (in shares)	34,597,688	34,702,547	34,659,146	34,768,203
Earnings per share attributable to ExlService Holdings Inc. stockholders:
Basic (in dollars per share)	$ 0.24	$ 0.36	$ 0.90	$ 0.79
Diluted (in dollars per share)	$ 0.24	$ 0.36	$ 0.89	$ 0.78
Weighted average potentially dilutive considered anti-dilutive and not included in computing diluted earnings per share (in shares)	638,318	69	404,315	212,751