Summary of Short-term Investments (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Investments [Line Items]
Investments in mutual funds at fair value	$ 126,479	$ 186,842	$ 149,828
Term deposits with banks	413,566	466,625	$ 340,349
Fixed Maturity Plans (FMPs) of mutual funds, at cost		15,886
Total	$ 540,045	$ 669,353