Commitments, Guarantees and Risks - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Commitments And Contingencies Disclosure [Abstract]
Operating lease expiration minimum period	3 years
Operating lease expiration maximum period	5 years
Operating lease rental expense based on straight-line basis	$ 254	$ 242	$ 234
Termination fees	$ 113
Expiration period of termination fee	3 years