Fair Value Measurements - Assets and Liabilities Recorded at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions		Jun. 30, 2018		Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Netting, Assets	[1],[2]	$ (27,075)		$ (36,394)
Netting Liabilities	[1],[2]	(27,075)		(36,394)
Trading assets		25,559		16,150
Trading liabilities		3,277		4,879
Precious metals [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Trading assets		9,212		2,274
Trading liabilities		0		524
Other asset-backed securities available-for-sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Trading assets		0		12
Derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Trading liabilities		2,295		2,633
Derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Trading assets		3,546		3,725
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		87,757		88,988
Netting, Assets	[3]	(30,241)		(40,874)	[4]
Net Balance, Assets		57,516		48,114
Gross Balance, Liabilities		55,931		68,270
Netting Liabilities	[3]	(31,253)		(40,217)
Net Balance, Liabilities		24,678		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		7,701	[5]	7,693	[4]
Net Balance, Liabilities		7,701	[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		982		2,246
Net Balance, Liabilities		982		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]	33,551		43,413
Netting Liabilities	[3],[5]	(31,253)		(40,217)
Net Balance, Liabilities	[5]	2,298		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]	11,302		24,438
Netting Liabilities	[3],[5]	0		0
Net Balance, Liabilities	[5]	11,302		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]	17,568		14,666
Netting Liabilities	[3],[5]	0		0
Net Balance, Liabilities	[5]	17,568		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]	3,110		2,951
Netting Liabilities	[3],[5]	0		0
Net Balance, Liabilities	[5]	3,110		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]	702		722
Netting Liabilities	[3],[5]	0		0
Net Balance, Liabilities	[5]	702		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]	810		584
Netting Liabilities	[3],[5]	0		0
Net Balance, Liabilities	[5]	810		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]	59		52
Netting Liabilities	[3],[5]	0		0	[6]
Net Balance, Liabilities	[5],[6]	59		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]	(31,253)		(40,217)
Net Balance, Liabilities	[5]	(31,253)		(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		1,315	[4]	2,032	[5]
Net Balance, Liabilities		1,315	[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]	12,382		12,886
Net Balance, Liabilities	[4]	12,382		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]	395		80
Net Balance, Assets	[4]	395		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		4,874		3,723
Net Balance, Assets		4,874	[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		131		129
Net Balance, Assets		131	[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		17		16
Net Balance, Assets		17	[4]	16
Fair Value, Measurements, Recurring [Member] | Trading assets, excluding derivatives [Member] | Student Loan 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		5,884		4,377
Net Balance, Assets		5,884	[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	[7]			12
Net Balance, Assets	[7]			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		9,212		2,274
Net Balance, Assets		9,212	[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]	33,936		45,297
Netting, Assets	[3],[5]	(30,241)		(40,874)
Net Balance, Assets	[5]	3,695		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]	10,058		24,237
Netting, Assets	[3],[5]	0		0
Net Balance, Assets	[5]	10,058		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]	18,276		15,760
Netting, Assets	[3],[5]	0		0
Net Balance, Assets	[5]	18,276		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]	3,799		4,084
Netting, Assets	[3],[5]	0		0
Net Balance, Assets	[5]	3,799		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]	836		554
Netting, Assets	[3],[5]	0		0
Net Balance, Assets	[5]	836		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]	959		656
Netting, Assets	[3],[5]	0		0
Net Balance, Assets	[5]	959		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]	8		6
Netting, Assets	[3],[5],[6]	0		0
Net Balance, Assets	[5],[6]	8		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]	(30,241)		(40,874)
Net Balance, Assets	[5]	(30,241)		(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]	28,485		29,060
Net Balance, Assets	[8]	28,485		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]	2,389		902
Net Balance, Assets	[8]	2,389		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]	47		51
Net Balance, Assets	[8]	47		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]	107		510
Net Balance, Assets	[8]	107		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]	90		471
Net Balance, Assets	[4]	90		471
Fair Value, Measurements, Recurring [Member] | Other assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets	[9]	12		15
Net Balance, Assets	[9]	12		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]	190
Net Balance, Assets	[7]	190
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]	93
Net Balance, Assets	[7],[10]	93
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		29,804		27,526
Gross Balance, Liabilities		1,135		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		975		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]	160		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]	132		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]	0		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]	28		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		4,732		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 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		5,674		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	[7]			0
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]	112		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]	7		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]	1		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]	104		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]	17,154		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]	2,132		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		55,554		59,103
Gross Balance, Liabilities		53,170		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		6,825	[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		7		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]	33,198		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]	11,170		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]	17,566		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]	2,988		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]	674		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]	800		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		1,315	[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]	11,825		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]	395		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		142		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		17		16
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Trading assets, excluding derivatives [Member] | Student Loan Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Gross Balance, Assets		92		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		210		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	[7]			12
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		9,212		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]	33,571		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]	10,051		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]	18,274		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]	3,675		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]	732		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]	839		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]	11,331		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]	257		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]	47		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]	90		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]	190
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		2,306		2,359
Gross Balance, Liabilities		1,626		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]	876		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]	557		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]	2		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		110		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		(51)		(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		876	[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]	193		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]	122		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]	10		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]	59		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]	557		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		131		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		0		0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Trading assets, excluding derivatives [Member] | Student Loan 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 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	[7]			0
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]	253		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]	124		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]	120		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]	8		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]	107		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]	12		$ 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 $3,546 million and $3,725 million and trading derivative liabilities of $2,295 million and $2,633 million at June 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 certain Visa Class B Shares.

[7] See Note 3, "Securities," and Note 21, "New Accounting Pronouncements," for additional information. Beginning January 1, 2018, all equity investments are being recorded together as a component of other assets.

[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.