Schedule of Segment Wise Revenues and Gross Profits (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Segment Reporting Information [Line Items]
Net revenues	$ 187,773	$ 186,407	$ 178,979	$ 170,744	$ 172,420	$ 167,627	$ 156,985	$ 145,372	$ 723,903	[1]	$ 642,404	[1]	$ 532,133	[1]
Gross profit	84,855	84,819	73,858	71,452	72,618	66,734	56,785	50,812	314,984		246,949		212,091
Selling, general and administrative expenses	28,131	29,036	18,931	26,946	19,638	36,679	27,781	24,623	103,044		108,721		91,556
Income from operations									211,940		138,228		120,535
Applications Outsourcing
Segment Reporting Information [Line Items]
Net revenues									544,694		478,927		402,526
Gross profit									217,732		164,812		141,168
KPO
Segment Reporting Information [Line Items]
Net revenues									110,455		97,777		79,589
Gross profit									68,756		57,291		50,579
E-Business
Segment Reporting Information [Line Items]
Net revenues									54,397		52,854		38,006
Gross profit									22,504		19,899		14,441
Teamsourcing
Segment Reporting Information [Line Items]
Net revenues									14,357		12,846		12,012
Gross profit									$ 5,992		$ 4,947		$ 5,903

[1] Net revenues are attributed to regions based upon customer location.