Contingent Liabilities and Commitments - Additional Information (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Commitment And Contingencies [Line Items]
Contingent liability	$ 506,888,000	$ 520,375,000	$ 502,611,000	$ 495,849,000
Contingent liabilities for guarantees of consolidated subsidiaries	3,000,000
Escrow Account Deposit
Commitment And Contingencies [Line Items]
Contingent liability	800,700,000
Exchange Traded Funds
Commitment And Contingencies [Line Items]
Contingent liability	$ 719,300,000