Schedule of Financial Instruments Owned and Pledged as Collateral (Detail) - USD ($) $ in Millions		Jun. 30, 2016	Dec. 31, 2015
Financial Instruments Owned and Pledged as Collateral [Line Items]
Amount of Repurchase Agreements Secured by Trading Assets		$ 787	$ 950
Repurchase Agreements [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Trading Securities Pledged as Collateral	[1]	821	986
Derivative [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Trading Securities Pledged as Collateral		467	393
Equity Trading [Member]
Financial Instruments Owned and Pledged as Collateral [Line Items]
Trading Securities Pledged as Collateral		$ 40	$ 40

[1] Repurchase agreements secured by collateral totaled $787 million and $950 million at June 30, 2016 and December 31, 2015, respectively.