Guarantee Arrangements and Pledged Assets and Collateral - Summary of Credit Ratings of Credit Risk Related Guarantees (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	$ 214,463
Sell-protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	206,309
Single name CDS [Member]
Credit Derivatives [Line Items]
Average Life in years	2 years 4 months 24 days	[1]
Single name CDS [Member] | Sell-protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	145,876	[1]
Structured CDS [Member]
Credit Derivatives [Line Items]
Average Life in years	2 years	[1]
Structured CDS [Member] | Sell-protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	26,334	[1]
Index credit derivatives [Member]
Credit Derivatives [Line Items]
Average Life in years	3 years 6 months	[1]
Index credit derivatives [Member] | Sell-protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	22,102	[1]
Total return swaps [Member]
Credit Derivatives [Line Items]
Average Life in years	8 years 1 month 6 days	[1]
Total return swaps [Member] | Sell-protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	11,997	[1]
Standby Letters of Credit [Member]
Credit Derivatives [Line Items]
Average Life in years	1 year 2 months 12 days	[2]
Credit Ratings of the Obligors or the Transactions	8,154	[2]
External Credit Rating, Investment Grade [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	183,114
External Credit Rating, Investment Grade [Member] | Sell-protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	176,506
External Credit Rating, Investment Grade [Member] | Single name CDS [Member] | Sell-protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	121,617	[1]
External Credit Rating, Investment Grade [Member] | Structured CDS [Member] | Sell-protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	23,337	[1]
External Credit Rating, Investment Grade [Member] | Index credit derivatives [Member] | Sell-protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	21,573	[1]
External Credit Rating, Investment Grade [Member] | Total return swaps [Member] | Sell-protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	9,979	[1]
External Credit Rating, Investment Grade [Member] | Standby Letters of Credit [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	6,608	[2]
External Credit Rating, Non Investment Grade [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	31,349
External Credit Rating, Non Investment Grade [Member] | Sell-protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	29,803
External Credit Rating, Non Investment Grade [Member] | Single name CDS [Member] | Sell-protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	24,259	[1]
External Credit Rating, Non Investment Grade [Member] | Structured CDS [Member] | Sell-protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	2,997	[1]
External Credit Rating, Non Investment Grade [Member] | Index credit derivatives [Member] | Sell-protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	529	[1]
External Credit Rating, Non Investment Grade [Member] | Total return swaps [Member] | Sell-protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	2,018	[1]
External Credit Rating, Non Investment Grade [Member] | Standby Letters of Credit [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	$ 1,546	[2]

[1] The credit ratings in the table represent external credit ratings for classification as investment grade and non-investment grade.

[2] External ratings for most of the obligors are not available. Presented above are the internal credit ratings which are developed using similar methodologies and rating scale equivalent to external credit ratings for purposes of classification as investment grade and non-investment grade.