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, 2016	Dec. 31, 2015
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions		$ 66,721	$ 103,647
Credit Ratings of the Obligors or the Transactions, Total		66,721
Sell Protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions		$ 58,329
Single name credit default swap [Member] | Sell Protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Average Life in years	[1]	2 years 3 months 26 days
Credit Ratings of the Obligors or the Transactions	[1]	$ 44,445
Structured CDS [Member] | Sell Protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Average Life in years	[1]	7 months 2 days
Credit Ratings of the Obligors or the Transactions	[1]	$ 3,841
Index credit derivatives [Member] | Sell Protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Average Life in years	[1]	3 years 7 months 5 days
Credit Ratings of the Obligors or the Transactions	[1]	$ 6,948
Total return swaps [Member] | Sell Protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Average Life in years	[1]	2 years 4 months 9 days
Credit Ratings of the Obligors or the Transactions	[1]	$ 3,095
Standby Letters of Credit [Member]
Credit Derivatives [Line Items]
Average Life in years	[2]	1 year 2 months 15 days
Credit Ratings of the Obligors or the Transactions	[2]	$ 8,392
External Credit Rating, Investment Grade [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions, Total		46,225
External Credit Rating, Investment Grade [Member] | Sell Protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions		40,731
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]	31,030
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]	3,491
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]	3,487
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]	2,723
External Credit Rating, Investment Grade [Member] | Standby Letters of Credit [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions	[2]	5,494
External Credit Rating, Non Investment Grade [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions, Total		20,496
External Credit Rating, Non Investment Grade [Member] | Sell Protection Credit Derivatives [Member]
Credit Derivatives [Line Items]
Credit Ratings of the Obligors or the Transactions		17,598
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]	13,415
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]	350
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]	3,461
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]	372
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]	$ 2,898

[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.