Schedule of Assets and Liabilities Measured at Fair Value (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Short term investments	$ 275,183	$ 510,816
Foreign exchange derivative contracts	5,599	782
Total current assets	280,782	511,598
Current liabilities:
Foreign exchange derivative contracts	5,349	7,516
Total current liabilities	5,349	7,516
Liquid Mutual Funds
Current assets:
Short term investments	175,175	466,468
Fixed Maturity Plan Funds
Current assets:
Short term investments	0	3,952
Certificate of Deposits with Bank and Others
Current assets:
Short term investments	0	40,396
Fixed Deposits with Banks
Current assets:
Short term investments	100,008	0
Foreign Exchange Contracts
Current assets:
Foreign exchange derivative contracts	5,599	782
Current liabilities:
Foreign exchange derivative contracts	5,349	7,516
Quoted Prices in Active Markets for Identical Assets (Level 1)
Current assets:
Total current assets	275,183	466,468
Current liabilities:
Total current liabilities	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Liquid Mutual Funds
Current assets:
Short term investments	175,175	466,468
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed Maturity Plan Funds
Current assets:
Short term investments	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Certificate of Deposits with Bank and Others
Current assets:
Short term investments	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed Deposits with Banks
Current assets:
Short term investments	100,008	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign Exchange Contracts
Current assets:
Foreign exchange derivative contracts	0	0
Current liabilities:
Foreign exchange derivative contracts	0	0
Significant Other Observable Inputs (Level 2)
Current assets:
Total current assets	5,599	45,130
Current liabilities:
Total current liabilities	5,349	7,516
Significant Other Observable Inputs (Level 2) | Liquid Mutual Funds
Current assets:
Short term investments	0	0
Significant Other Observable Inputs (Level 2) | Fixed Maturity Plan Funds
Current assets:
Short term investments	0	3,952
Significant Other Observable Inputs (Level 2) | Certificate of Deposits with Bank and Others
Current assets:
Short term investments	0	40,396
Significant Other Observable Inputs (Level 2) | Fixed Deposits with Banks
Current assets:
Short term investments	0	0
Significant Other Observable Inputs (Level 2) | Foreign Exchange Contracts
Current assets:
Foreign exchange derivative contracts	5,599	782
Current liabilities:
Foreign exchange derivative contracts	5,349	7,516
Significant Unobservable Inputs (Level 3)
Current assets:
Total current assets	0	0
Current liabilities:
Total current liabilities	0	0
Significant Unobservable Inputs (Level 3) | Liquid Mutual Funds
Current assets:
Short term investments	0	0
Significant Unobservable Inputs (Level 3) | Fixed Maturity Plan Funds
Current assets:
Short term investments	0	0
Significant Unobservable Inputs (Level 3) | Certificate of Deposits with Bank and Others
Current assets:
Short term investments	0	0
Significant Unobservable Inputs (Level 3) | Fixed Deposits with Banks
Current assets:
Short term investments	0	0
Significant Unobservable Inputs (Level 3) | Foreign Exchange Contracts
Current assets:
Foreign exchange derivative contracts	0	0
Current liabilities:
Foreign exchange derivative contracts	$ 0	$ 0