Fair Value Measurements - Assets and Liabilities Recorded at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions		Sep. 30, 2018		Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Netting, Assets	[1],[2]	$ (24,613)		$ (36,394)
Netting Liabilities	[1],[2]	(24,613)		(36,394)
Trading assets		26,556		16,150
Trading liabilities		3,948		4,879
Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Trading assets		752		12
Precious metals [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Trading assets		9,945		2,274
Trading liabilities		0		524
Derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Trading liabilities		2,343		2,633
Derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Trading assets		3,144		3,725
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		86,653		88,988
Netting, Assets	[3]	(28,046)		(40,874)	[4]
Net Balance, Assets		58,607		48,114
Gross Balance, Liabilities		53,201		68,270
Netting Liabilities	[3]	(28,130)		(40,217)
Net Balance, Liabilities		25,071		28,053
Fair Value, Measurements, Recurring [Member] | Domestic Deposits [Member] | Domestic Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities		7,980	[5]	7,693	[4]
Net Balance, Liabilities		7,980	[5]	7,693	[4]
Fair Value, Measurements, Recurring [Member] | Trading liabilities, excluding derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities		1,605		2,246
Net Balance, Liabilities		1,605		2,246
Fair Value, Measurements, Recurring [Member] | Derivative financial liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	30,438		43,413
Netting Liabilities	[3],[5]	(28,130)		(40,217)
Net Balance, Liabilities	[5]	2,308		3,196
Fair Value, Measurements, Recurring [Member] | Derivative financial liabilities [Member] | Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	10,648		24,438
Netting Liabilities	[3],[5]	0		0
Net Balance, Liabilities	[5]	10,648		24,438
Fair Value, Measurements, Recurring [Member] | Derivative financial liabilities [Member] | Foreign exchange contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	14,595		14,666
Netting Liabilities	[3],[5]	0		0
Net Balance, Liabilities	[5]	14,595		14,666
Fair Value, Measurements, Recurring [Member] | Derivative financial liabilities [Member] | Equity contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	3,377		2,951
Netting Liabilities	[3],[5]	0		0
Net Balance, Liabilities	[5]	3,377		2,951
Fair Value, Measurements, Recurring [Member] | Derivative financial liabilities [Member] | Precious metals contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	851		722
Netting Liabilities	[3],[5]	0		0
Net Balance, Liabilities	[5]	851		722
Fair Value, Measurements, Recurring [Member] | Derivative financial liabilities [Member] | Credit contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	916		584
Netting Liabilities	[3],[5]	0		0
Net Balance, Liabilities	[5]	916		584
Fair Value, Measurements, Recurring [Member] | Derivative financial liabilities [Member] | Other Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5],[6]	51		52
Netting Liabilities	[3],[5]	0		0	[6]
Net Balance, Liabilities	[5],[6]	51		52
Fair Value, Measurements, Recurring [Member] | Derivative financial liabilities [Member] | Derivatives netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	0		0
Netting Liabilities	[3],[5]	(28,130)		(40,217)
Net Balance, Liabilities	[5]	(28,130)		(40,217)
Fair Value, Measurements, Recurring [Member] | Short-term borrowings [Member] | Long-term debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities		916	[4]	2,032	[5]
Net Balance, Liabilities		916	[4]	2,032	[5]
Fair Value, Measurements, Recurring [Member] | Long-term Debt [Member] | Long-term debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[4]	12,262		12,886
Net Balance, Liabilities	[4]	12,262		12,886
Fair Value, Measurements, Recurring [Member] | Securities purchased under agreements to resell [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[4]	117		80
Net Balance, Assets	[4]	117		80
Fair Value, Measurements, Recurring [Member] | Trading assets, excluding derivatives [Member] | U.S. Treasury, U.S. Government agencies and sponsored enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		4,170		3,723
Net Balance, Assets		4,170	[4]	3,723
Fair Value, Measurements, Recurring [Member] | Trading assets, excluding derivatives [Member] | Collateralized debt obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		112		129
Net Balance, Assets		112	[4]	129
Fair Value, Measurements, Recurring [Member] | Trading assets, excluding derivatives [Member] | Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		16		16
Net Balance, Assets		16	[4]	16
Fair Value, Measurements, Recurring [Member] | Trading assets, excluding derivatives [Member] | Student loan asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		92		91
Net Balance, Assets		92	[4]	91
Fair Value, Measurements, Recurring [Member] | Trading assets, excluding derivatives [Member] | Corporate and other domestic debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		1,803		1,803
Net Balance, Assets		1,803	[4]	1,803
Fair Value, Measurements, Recurring [Member] | Trading assets, excluding derivatives [Member] | Foreign debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		6,522		4,377
Net Balance, Assets		6,522	[4]	4,377
Fair Value, Measurements, Recurring [Member] | Trading assets, excluding derivatives [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		752		12	[7]
Net Balance, Assets	[7]	752		12
Fair Value, Measurements, Recurring [Member] | Trading assets, excluding derivatives [Member] | Precious metals [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		9,945		2,274
Net Balance, Assets		9,945	[4]	2,274
Fair Value, Measurements, Recurring [Member] | Derivative financial assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	31,279		45,297
Netting, Assets	[3],[5]	(28,046)		(40,874)
Net Balance, Assets	[5]	3,233		4,423
Fair Value, Measurements, Recurring [Member] | Derivative financial assets [Member] | Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	9,765		24,237
Netting, Assets	[3],[5]	0		0
Net Balance, Assets	[5]	9,765		24,237
Fair Value, Measurements, Recurring [Member] | Derivative financial assets [Member] | Foreign exchange contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	15,475		15,760
Netting, Assets	[3],[5]	0		0
Net Balance, Assets	[5]	15,475		15,760
Fair Value, Measurements, Recurring [Member] | Derivative financial assets [Member] | Equity contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	4,246		4,084
Netting, Assets	[3],[5]	0		0
Net Balance, Assets	[5]	4,246		4,084
Fair Value, Measurements, Recurring [Member] | Derivative financial assets [Member] | Precious metals contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	838		554
Netting, Assets	[3],[5]	0		0
Net Balance, Assets	[5]	838		554
Fair Value, Measurements, Recurring [Member] | Derivative financial assets [Member] | Credit contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	949		656
Netting, Assets	[3],[5]	0		0
Net Balance, Assets	[5]	949		656
Fair Value, Measurements, Recurring [Member] | Derivative financial assets [Member] | Other Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5],[6]	6		6
Netting, Assets	[3],[5],[6]	0		0
Net Balance, Assets	[5],[6]	6		6
Fair Value, Measurements, Recurring [Member] | Derivative financial assets [Member] | Derivatives netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	0		0
Netting, Assets	[3],[5]	(28,046)		(40,874)
Net Balance, Assets	[5]	(28,046)		(40,874)
Fair Value, Measurements, Recurring [Member] | Securities available-for-sale [Member] | U.S. Treasury, U.S. Government agencies and sponsored enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[8]	28,729		29,060
Net Balance, Assets	[8]	28,729		29,060
Fair Value, Measurements, Recurring [Member] | Securities available-for-sale [Member] | Foreign debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[8]	2,451		902
Net Balance, Assets	[8]	2,451		902
Fair Value, Measurements, Recurring [Member] | Securities available-for-sale [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[7],[8]			177
Net Balance, Assets	[7],[8]			177
Fair Value, Measurements, Recurring [Member] | Securities available-for-sale [Member] | Home Equity Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[8]	44		51
Net Balance, Assets	[8]	44		51
Fair Value, Measurements, Recurring [Member] | Securities available-for-sale [Member] | Other asset-backed securities available-for-sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[8]	105		510
Net Balance, Assets	[8]	105		510
Fair Value, Measurements, Recurring [Member] | Loans [Member] | Loans Receivable [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[4]	242		471
Net Balance, Assets	[4]	242		471
Fair Value, Measurements, Recurring [Member] | Other assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[9]	4		15
Net Balance, Assets	[9]	4		15
Fair Value, Measurements, Recurring [Member] | Other assets [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[7]	189
Net Balance, Assets	[7]	189
Fair Value, Measurements, Recurring [Member] | Other assets [Member] | Equity Securities Measured at Net Asset Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[7],[10]	81
Net Balance, Assets	[7],[10]	81
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		30,789		27,526
Gross Balance, Liabilities		1,823		1,889
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Domestic Deposits [Member] | Domestic Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities		0	[5]	0	[4]
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Trading liabilities, excluding derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities		1,605		1,722
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Derivative financial liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	218		167
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Derivative financial liabilities [Member] | Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	145		59
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Derivative financial liabilities [Member] | Foreign exchange contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	22		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Derivative financial liabilities [Member] | Equity contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Derivative financial liabilities [Member] | Precious metals contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	51		108
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Derivative financial liabilities [Member] | Credit contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Derivative financial liabilities [Member] | Other Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5],[6]	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Derivative financial liabilities [Member] | Derivatives netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Short-term borrowings [Member] | Long-term debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities		0	[4]	0	[5]
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Long-term Debt [Member] | Long-term debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[4]	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Securities purchased under agreements to resell [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[4]	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Trading assets, excluding derivatives [Member] | U.S. Treasury, U.S. Government agencies and sponsored enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		4,037		3,391
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Trading assets, excluding derivatives [Member] | Collateralized debt obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Trading assets, excluding derivatives [Member] | Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Trading assets, excluding derivatives [Member] | Student loan asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Trading assets, excluding derivatives [Member] | Corporate and other domestic debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Trading assets, excluding derivatives [Member] | Foreign debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		6,370		4,167
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Trading assets, excluding derivatives [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		752		0	[7]
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Trading assets, excluding derivatives [Member] | Precious metals [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Derivative financial assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	67		62
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Derivative financial assets [Member] | Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	3		6
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Derivative financial assets [Member] | Foreign exchange contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	0		4
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Derivative financial assets [Member] | Equity contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Derivative financial assets [Member] | Precious metals contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	64		52
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Derivative financial assets [Member] | Credit contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Derivative financial assets [Member] | Other Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5],[6]	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Derivative financial assets [Member] | Derivatives netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Securities available-for-sale [Member] | U.S. Treasury, U.S. Government agencies and sponsored enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[8]	17,311		19,056
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Securities available-for-sale [Member] | Foreign debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[8]	2,252		850
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Securities available-for-sale [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[7],[8]			0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Securities available-for-sale [Member] | Home Equity Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[8]	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Securities available-for-sale [Member] | Other asset-backed securities available-for-sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[8]	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Loans [Member] | Loans Receivable [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[4]	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Other assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[9]	0		0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Other assets [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[7]	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Other assets [Member] | Equity Securities Measured at Net Asset Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[7],[10]	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		53,495		59,103
Gross Balance, Liabilities		49,775		64,691
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Domestic Deposits [Member] | Domestic Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities		7,037	[5]	6,796	[4]
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Trading liabilities, excluding derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities		0		524
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Derivative financial liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	30,092		43,094
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Derivative financial liabilities [Member] | Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	10,503		24,379
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Derivative financial liabilities [Member] | Foreign exchange contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	14,571		14,664
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Derivative financial liabilities [Member] | Equity contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	3,313		2,859
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Derivative financial liabilities [Member] | Precious metals contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	800		614
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Derivative financial liabilities [Member] | Credit contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	905		578
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Derivative financial liabilities [Member] | Other Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5],[6]	0		0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Derivative financial liabilities [Member] | Derivatives netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	0		0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Short-term borrowings [Member] | Long-term debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities		916	[4]	2,032	[5]
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Long-term Debt [Member] | Long-term debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[4]	11,730		12,245
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Securities purchased under agreements to resell [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[4]	117		80
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Trading assets, excluding derivatives [Member] | U.S. Treasury, U.S. Government agencies and sponsored enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		133		332
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Trading assets, excluding derivatives [Member] | Collateralized debt obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		0		0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Trading assets, excluding derivatives [Member] | Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		0		16
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Trading assets, excluding derivatives [Member] | Student loan asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		0		91
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Trading assets, excluding derivatives [Member] | Corporate and other domestic debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		0		0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Trading assets, excluding derivatives [Member] | Foreign debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		152		210
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Trading assets, excluding derivatives [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		0		12	[7]
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Trading assets, excluding derivatives [Member] | Precious metals [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		9,945		2,274
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Derivative financial assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	31,056		44,934
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Derivative financial assets [Member] | Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	9,762		24,231
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Derivative financial assets [Member] | Foreign exchange contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	15,474		15,754
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Derivative financial assets [Member] | Equity contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	4,172		3,911
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Derivative financial assets [Member] | Precious metals contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	774		502
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Derivative financial assets [Member] | Credit contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	874		536
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Derivative financial assets [Member] | Other Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5],[6]	0		0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Derivative financial assets [Member] | Derivatives netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	0		0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Securities available-for-sale [Member] | U.S. Treasury, U.S. Government agencies and sponsored enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[8]	11,418		10,004
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Securities available-for-sale [Member] | Foreign debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[8]	199		52
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Securities available-for-sale [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[7],[8]			177
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Securities available-for-sale [Member] | Home Equity Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[8]	44		51
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Securities available-for-sale [Member] | Other asset-backed securities available-for-sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[8]	0		399
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Loans [Member] | Loans Receivable [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[4]	242		471
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[9]	0		0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other assets [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[7]	189
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Other assets [Member] | Equity Securities Measured at Net Asset Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[7],[10]	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		2,288		2,359
Gross Balance, Liabilities		1,603		1,690
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Domestic Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[11],[12]	943		897
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Long-term debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[11],[12]	532		641
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets				0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Foreign exchange contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[12]	(1)		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Equity contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[12]	10		81
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Credit contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		64		114
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		(45)		(46)
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Domestic Deposits [Member] | Domestic Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities		943	[5]	897	[4]
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Trading liabilities, excluding derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities		0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Derivative financial liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	128		152
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Derivative financial liabilities [Member] | Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Derivative financial liabilities [Member] | Foreign exchange contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	2		2
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Derivative financial liabilities [Member] | Equity contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	64		92
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Derivative financial liabilities [Member] | Precious metals contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Derivative financial liabilities [Member] | Credit contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	11		6
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Derivative financial liabilities [Member] | Other Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5],[6]	51		52
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Derivative financial liabilities [Member] | Derivatives netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[5]	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Short-term borrowings [Member] | Long-term debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities		0	[4]	0	[5]
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Long-term Debt [Member] | Long-term debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Liabilities	[4]	532		641
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Securities purchased under agreements to resell [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[4]	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Trading assets, excluding derivatives [Member] | U.S. Treasury, U.S. Government agencies and sponsored enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Trading assets, excluding derivatives [Member] | Collateralized debt obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		112		129
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Trading assets, excluding derivatives [Member] | Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		16		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Trading assets, excluding derivatives [Member] | Student loan asset-backed securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		92		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Trading assets, excluding derivatives [Member] | Corporate and other domestic debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		1,803		1,803
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Trading assets, excluding derivatives [Member] | Foreign debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Trading assets, excluding derivatives [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		0		0	[7]
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Trading assets, excluding derivatives [Member] | Precious metals [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Derivative financial assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	156		301
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Derivative financial assets [Member] | Interest rate contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Derivative financial assets [Member] | Foreign exchange contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	1		2
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Derivative financial assets [Member] | Equity contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	74		173
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Derivative financial assets [Member] | Precious metals contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Derivative financial assets [Member] | Credit contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	75		120
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Derivative financial assets [Member] | Other Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5],[6]	6		6
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Derivative financial assets [Member] | Derivatives netting [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[5]	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Securities available-for-sale [Member] | U.S. Treasury, U.S. Government agencies and sponsored enterprises [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[8]	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Securities available-for-sale [Member] | Foreign debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[8]	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Securities available-for-sale [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[7],[8]			0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Securities available-for-sale [Member] | Home Equity Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[8]	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Securities available-for-sale [Member] | Other asset-backed securities available-for-sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[8]	105		111
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Loans [Member] | Loans Receivable [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[4]	0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[9]	4		$ 15
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other assets [Member] | Equity securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[7]	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Other assets [Member] | Equity Securities Measured at Net Asset Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[7],[10]	$ 0

[1] Netting is performed at a counterparty level in cases where enforceable master netting agreements are in place, regardless of the type of derivative instrument. Therefore, we have not allocated netting to the different types of derivative instruments shown in the table above.

[2] Represents the netting of derivative receivable and payable balances for the same counterparty under enforceable netting agreements.

[3] Represents counterparty and cash collateral netting which allow the offsetting of amounts relating to certain contracts if certain conditions are met.

[4] See Note 10, "Fair Value Option," for additional information. Excluding the fair value movement on fair value option liabilities attributable to our own credit spread, which is recorded in other comprehensive income (loss), fair value option assets and liabilities are recorded at fair value through net income.

[5] Includes trading derivative assets of $3,144 million and $3,725 million and trading derivative liabilities of $2,343 million and $2,633 million at September 30, 2018 and December 31, 2017, respectively, as well as derivatives held for hedging and commitments accounted for as derivatives. See Note 9, "Derivatives," for additional information. Excluding changes in fair value of a derivative instrument associated with the effective portion of a qualifying cash flow hedge, which is recognized initially in other comprehensive income (loss), derivative assets and liabilities are recorded at fair value through net income.

[6] Consists of swap agreements entered into in conjunction with the sales of Visa Class B Shares.

[7] See Note 3, "Securities," and Note 21, "New Accounting Pronouncements," for additional information. The adoption of new accounting guidance resulted in a reclassification of certain equity investments to other assets as of January 1, 2018.

[8] Securities available-for-sale are recorded at fair value through other comprehensive income (loss).

[9] Represents contingent consideration receivable associated with the sale of a portion of our Private Banking business.

[10] Investments that are measured at fair value using the net asset value per share practical expedient have not been classified in the fair value hierarchy.

[11] Structured deposits and structured notes contain embedded derivative features whose fair value measurements contain significant Level 3 inputs.

[12] We are the client-facing entity and we enter into identical but opposite derivatives to transfer the resultant risks to our affiliates. With the exception of counterparty credit risks, we are market neutral. The corresponding intra-group derivatives are presented as equity derivatives and foreign exchange derivatives in the table.