Securities Financing Activities (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Components of collateralized financings [Abstract]
Securities Purchased under Agreements to Resell, Subject to Master Netting Arrangement	$ 308,068,000,000	$ 381,377,000,000
Carrying Value of Securities Purchased Under Resale Agreements That Have Been Netted	101,060,000,000	96,947,000,000
Securities Purchased under Agreements to Resell, Not Subject to Master Netting Arrangement	11,018,000,000	10,983,000,000
Securities Purchased under Agreements to Resell, Gross	319,086,000,000	392,360,000,000
Securities Borrowed	114,058,000,000	119,017,000,000
Securities Purchased under Agreements to Resell, Subject to Master Netting Arrangement, Net	207,008,000,000	284,430,000,000
Securities purchased under resale agreements	218,026,000,000	295,413,000,000
Securities financing activities (Numeric) [Abstract]
Federal funds sold and securities purchased under resale agreements, at fair value	218,343,000,000	296,296,000,000
Securities Borrowed, Amount Not Offset Against Collateral, Gross	3,600,000,000	6,900,000,000
Securities Borrowed, Amount Offset Against Collateral, Gross	110,497,000,000	112,087,000,000
Securities Purchased under Agreements to Resell, Collateral, Obligation to Return Securities	(204,268,000,000)	(282,468,000,000)
Securities Borrowed, Collateral, Obligation to Return Securities	(106,847,000,000)	(108,777,000,000)
Securities Purchased under Agreements to Resell, Collateral, Obligation to Return Cash	(1,036,000,000)	(998,000,000)
Securities Borrowed, Collateral, Obligation to Return Cash	0	0
Securities Purchased under Agreements to Resell, Amount Offset Against Collateral	1,704,000,000	964,000,000
Securities Borrowed, Amount Offset Against Collateral	3,650,000,000	3,310,000,000
Securities Sold under Agreements to Repurchase, Subject to Master Netting Arrangement	313,969,000,000	301,352,000,000
Securities Sold under Agreements to Repurchase, Not Subject to Master Netting Arrangement	9,889,000,000	11,155,000,000
Securities Sold under Agreements to Repurchase, Gross	323,858,000,000	312,507,000,000
Carrying Value of Securities Sold Under Repurchase Agreements That Have Been Netted	(101,060,000,000)	(96,947,000,000)
Securities Sold under Agreements to Repurchase	222,798,000,000	215,560,000,000
Securities loaned	0	0
Securities Sold under Agreements to Repurchase, Subject to Master Netting Arrangement, Net	212,909,000,000	204,405,000,000
Securities Loaned, Amount Not Offset Against Collateral, Gross	1,300,000,000	900,000,000
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Securities	(210,582,000,000)	(202,925,000,000)
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Cash	(43,000,000)	(162,000,000)
Securities Sold under Agreements to Repurchase, Amount Offset Against Collateral	2,284,000,000	1,318,000,000
Securities Loaned, Amount Offset Against Collateral, Gross	30,203,000,000	29,569,000,000
Securities Loaned, Collateral, Right to Reclaim Securities	(29,343,000,000)	(28,998,000,000)
Securities Loaned, Collateral, Right to Reclaim Cash	0	0
Securities Loaned, Amount Offset Against Collateral	860,000,000	571,000,000
Transfers Accounted for as Secured Borrowings, Assets, Carrying Amount	10,000,000,000	9,600,000,000
Securities-For-Securities Borrow Versus Pledge Transactions [Member]
Securities financing activities (Numeric) [Abstract]
Securities loaned	6,857,000,000	6,876,000,000
Fair value
Components of collateralized financings [Abstract]
Securities Borrowed	5,400,000,000	10,200,000,000
Securities financing activities (Numeric) [Abstract]
Federal funds sold and securities purchased under resale agreements, at fair value	25,600,000,000	24,300,000,000
Fair value | Fair Value, Measurements, Recurring [Member]
Securities financing activities (Numeric) [Abstract]
Federal funds purchased and securities loaned or sold under repurchase agreements	4,380,000,000	4,388,000,000
Fair value | Fair Value, Measurements, Recurring [Member] | Securities Sold under Agreements to Repurchase [Member]
Securities financing activities (Numeric) [Abstract]
Federal funds purchased and securities loaned or sold under repurchase agreements	3,935,000,000	3,931,000,000
Fair value | Fair Value, Measurements, Recurring [Member] | Securities Loaned [Member]
Securities financing activities (Numeric) [Abstract]
Federal funds purchased and securities loaned or sold under repurchase agreements	$ 445,000,000	$ 457,000,000