Segment and Geographical Information - Revenues and Cost of Revenues for Company's Reportable Segments (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) operating_segment	Jun. 30, 2016 USD ($)
Revenues and cost of revenues for Company's reportable segments [Line Items]
Revenues, net	$ 189,057	$ 170,478	$ 372,090	$ 337,514
Cost of revenues (exclusive of depreciation and amortization)	125,449	112,026	245,568	220,405
Gross profit	63,608	58,452	126,522	117,109
Operating expenses	47,479	42,216	94,491	84,421
Foreign exchange gain, interest expense and other income, net	5,072	7,147	9,518	10,410
Income tax expense	823	7,008	4,383	12,903
Net income	20,378	16,375	$ 37,166	30,195
Number of operating segments, industry focused | operating_segment			5
Number of capability operating segments | operating_segment			1
Insurance
Revenues and cost of revenues for Company's reportable segments [Line Items]
Revenues, net	58,255	50,597	$ 114,176	98,895
Cost of revenues (exclusive of depreciation and amortization)	40,976	36,451	79,305	70,719
Gross profit	17,279	14,146	34,871	28,176
Healthcare
Revenues and cost of revenues for Company's reportable segments [Line Items]
Revenues, net	18,923	17,442	37,855	33,830
Cost of revenues (exclusive of depreciation and amortization)	12,250	11,008	24,436	21,553
Gross profit	6,673	6,434	13,419	12,277
Travel, Transportation and Logistics
Revenues and cost of revenues for Company's reportable segments [Line Items]
Revenues, net	17,835	17,545	34,878	35,104
Cost of revenues (exclusive of depreciation and amortization)	10,473	10,801	20,697	21,264
Gross profit	7,362	6,744	14,181	13,840
Finance and Accounting
Revenues and cost of revenues for Company's reportable segments [Line Items]
Revenues, net	21,038	19,284	42,052	39,103
Cost of revenues (exclusive of depreciation and amortization)	12,955	11,929	25,853	23,373
Gross profit	8,083	7,355	16,199	15,730
All Other
Revenues and cost of revenues for Company's reportable segments [Line Items]
Revenues, net	21,447	26,001	42,563	52,007
Cost of revenues (exclusive of depreciation and amortization)	14,697	16,293	29,141	33,181
Gross profit	6,750	9,708	13,422	18,826
Analytics
Revenues and cost of revenues for Company's reportable segments [Line Items]
Revenues, net	51,559	39,609	100,566	78,575
Cost of revenues (exclusive of depreciation and amortization)	34,098	25,544	66,136	50,315
Gross profit	17,461	14,065	34,430	28,260
BPM and Related Services
Revenues and cost of revenues for Company's reportable segments [Line Items]
Revenues, net	137,498	130,869	271,524	258,939
Analytics Services
Revenues and cost of revenues for Company's reportable segments [Line Items]
Revenues, net	$ 51,559	$ 39,609	$ 100,566	$ 78,575