Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Summary of Credit Ratings of Credit Risk Related Guarantees (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions		$ 103,647	$ 128,894
Credit Ratings of the Obligors or the Transactions, Total		100,285
Sell Protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions		$ 91,435
Single name credit default swap [Member] | Sell Protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Average Life in years	[1]	2 years 4 months 29 days
Credit Ratings of the Obligors or the Transactions	[1]	$ 71,810
Structured CDS [Member] | Sell Protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Average Life in years	[1]	1 year 4 months
Credit Ratings of the Obligors or the Transactions	[1]	$ 5,584
Index credit derivatives [Member] | Sell Protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Average Life in years	[1]	3 years 5 months 17 days
Credit Ratings of the Obligors or the Transactions	[1]	$ 10,851
Total return swaps [Member] | Sell Protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Average Life in years	[1]	2 years 7 months 3 days
Credit Ratings of the Obligors or the Transactions	[1]	$ 3,190
Standby Letters of Credit [Member]
Credit Derivatives [Line Items]
Average Life in years	[2]	1 year 1 month 17 days
Credit Ratings of the Obligors or the Transactions	[2]	$ 8,850
External Credit Rating, Investment Grade [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions, Total		64,101
External Credit Rating, Investment Grade [Member] | Sell Protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions		57,909
External Credit Rating, Investment Grade [Member] | Single name credit default swap [Member] | Sell Protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	[1]	46,286
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	[1]	5,016
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	[1]	3,838
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	[1]	2,769
External Credit Rating, Investment Grade [Member] | Standby Letters of Credit [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	[2]	6,192
External Credit Rating, Non Investment Grade [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions, Total		36,184
External Credit Rating, Non Investment Grade [Member] | Sell Protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions		33,526
External Credit Rating, Non Investment Grade [Member] | Single name credit default swap [Member] | Sell Protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	[1]	25,524
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	[1]	568
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	[1]	7,013
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	[1]	421
External Credit Rating, Non Investment Grade [Member] | Standby Letters of Credit [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	[2]	$ 2,658

[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.