Summary of Short-term Investments (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Investments [Line Items]
Investments in mutual funds at fair value	$ 94,503	$ 186,842
Term deposits with banks	409,084	466,625
Fixed Maturity Plans (FMPs) of mutual funds, at cost		15,886
Total	$ 503,587	$ 669,353