Fair Value (Schedule Of Fair Value Measurements On A Recurring Basis) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012		Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	$ 611		$ 707
Reduction in Assets From Netting and the Result of Cash Collateral Deposited with Derivative Counterparties	854
Reduction in Liabilities From Netting and the Result of Cash Collateral Received From Derivative Counterparties	367
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	107,129		99,832
Derivative Assets	3,435		6,366
Other Assets, Fair Value Disclosure	51		110
Assets, Fair Value Disclosure	111,226		107,015
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	3,814		6,690
Other Liabilities, Fair Value Disclosure	49		130
Liabilities, Fair Value Disclosure	3,863		6,820
Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	3		1,728
Derivative Assets	0		0
Other Assets, Fair Value Disclosure	49		110
Assets, Fair Value Disclosure	510		2,407
Derivative Financial Instruments, Liabilities, Fair Value Disclosure
Other Liabilities, Fair Value Disclosure	49		110
Liabilities, Fair Value Disclosure	49		110
Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Exchange Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	0		0
Derivative Financial Instruments, Liabilities, Fair Value Disclosure
Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Interest Rate Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	0		0
Derivative Financial Instruments, Liabilities, Fair Value Disclosure
Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member] | Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets			0
Derivative Financial Instruments, Liabilities, Fair Value Disclosure
Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	100,707		89,591
Derivative Assets	6,832		13,841
Other Assets, Fair Value Disclosure	2		0
Assets, Fair Value Disclosure	107,694		103,570
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	6,652		14,162
Other Liabilities, Fair Value Disclosure	0		0
Liabilities, Fair Value Disclosure	6,652		14,162
Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Exchange Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	6,646		12,045
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	6,351		12,191
Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Interest Rate Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	186		1,795
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	301		1,970
Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets			1
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	0		1
Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	6,518
Liabilities, Fair Value Disclosure	109
Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	6,419		8,513
Derivative Assets	99		178
Other Assets, Fair Value Disclosure	0		0
Assets, Fair Value Disclosure	6,518		8,691
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	109		181
Other Liabilities, Fair Value Disclosure	0		20
Liabilities, Fair Value Disclosure	109		201
Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Foreign Exchange Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	99		168
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	100		161
Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Interest Rate Contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	0		10
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	0		11
Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member] | Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets			0
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	9		9
Netting and Collateral [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Assets	(3,496)	[1]	(7,653)	[1]
Other Assets, Fair Value Disclosure	0		0
Assets, Fair Value Disclosure	(3,496)	[1]	(7,653)	[1]
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	(2,947)	[1]	(7,653)	[1]
Other Liabilities, Fair Value Disclosure	0		0
Liabilities, Fair Value Disclosure	(2,947)	[1]	(7,653)	[1]
US Government Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	20		20
US Government Securities [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	20		20
Non-US Government Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	366		498
Non-US Government Securities [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	366		498
US Treasury and Federal Agencies, Direct Obligations [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	870		2,836
US Treasury and Federal Agencies, Direct Obligations [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	3		1,727
US Treasury and Federal Agencies, Direct Obligations [Member] | Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	867		1,109
US Treasury and Federal Agencies, Direct Obligations [Member] | Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure
US Treasury and Federal Agencies, Mortgage-backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	32,003		30,021
US Treasury and Federal Agencies, Mortgage-backed Securities [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
US Treasury and Federal Agencies, Mortgage-backed Securities [Member] | Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	31,097		28,832
US Treasury and Federal Agencies, Mortgage-backed Securities [Member] | Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	906		1,189
Asset-backed Securities, Student Loans [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	16,537		16,545
Asset-backed Securities, Student Loans [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Asset-backed Securities, Student Loans [Member] | Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	16,059		15,685
Asset-backed Securities, Student Loans [Member] | Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	478		860
Asset-backed Securities, Credit Cards [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	9,966		10,487
Asset-backed Securities, Credit Cards [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Asset-backed Securities, Credit Cards [Member] | Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	9,728		10,396
Asset-backed Securities, Credit Cards [Member] | Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	238		91
Asset-backed Securities, Sub-prime [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	1,379		1,404
Asset-backed Securities, Sub-prime [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Asset-backed Securities, Sub-prime [Member] | Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	1,379		1,404
Asset-backed Securities, Sub-prime [Member] | Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Asset-backed Securities, Other [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	4,126		3,465
Asset-backed Securities, Other [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Asset-backed Securities, Other [Member] | Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	666		667
Asset-backed Securities, Other [Member] | Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	3,460		2,798
Asset-backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	32,008		31,901
Asset-backed Securities [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Asset-backed Securities [Member] | Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	27,832		28,152
Asset-backed Securities [Member] | Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	4,176		3,749
Non-US Debt Securities, Mortgage-Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	11,044		10,875
Non-US Debt Securities, Mortgage-Backed Securities [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Non-US Debt Securities, Mortgage-Backed Securities [Member] | Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	10,759		9,418
Non-US Debt Securities, Mortgage-Backed Securities [Member] | Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	285		1,457
Non-US Debt Securities, Asset-Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	5,920		4,303
Non-US Debt Securities, Asset-Backed Securities [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Non-US Debt Securities, Asset-Backed Securities [Member] | Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	5,243		2,535
Non-US Debt Securities, Asset-Backed Securities [Member] | Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	677		1,768
Non-US Debt Securities, Government Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	2,986		1,671
Non-US Debt Securities, Government Securities [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Non-US Debt Securities, Government Securities [Member] | Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	2,986		1,671
Non-US Debt Securities, Government Securities [Member] | Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Non-US Debt Securities, Other [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	4,034		2,825
Non-US Debt Securities, Other [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Non-US Debt Securities, Other [Member] | Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	3,840		2,754
Non-US Debt Securities, Other [Member] | Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	194		71
Non U S Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	23,984		19,674
Non U S Debt Securities [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Non U S Debt Securities [Member] | Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	22,828		16,378
Non U S Debt Securities [Member] | Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	1,156		3,296
State And Political Subdivisions [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	7,304		7,047
State And Political Subdivisions [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
State And Political Subdivisions [Member] | Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	7,256		6,997
State And Political Subdivisions [Member] | Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	48		50
Collateralized Mortgage Obligations [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	4,845		3,980
Collateralized Mortgage Obligations [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Collateralized Mortgage Obligations [Member] | Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	4,721		3,753
Collateralized Mortgage Obligations [Member] | Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	124		227
Other U.S. Debt Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	225		189
Available-for-sale Securities, Fair Value Disclosure	5,104		3,615
Other U.S. Debt Securities [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	72		51
Available-for-sale Securities, Fair Value Disclosure	0		0
Other U.S. Debt Securities [Member] | Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	153		138
Available-for-sale Securities, Fair Value Disclosure	5,095		3,613
Other U.S. Debt Securities [Member] | Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	9		2
U.S. Equity Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	881		640
U.S. Equity Securities [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
U.S. Equity Securities [Member] | Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	881		640
U.S. Equity Securities [Member] | Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		0
Non-US Equity Securities [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	130		118
Non-US Equity Securities [Member] | Quoted Market Prices In Active Markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	0		1
Non-US Equity Securities [Member] | Pricing Methods With Significant Observable Market Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	130		117
Non-US Equity Securities [Member] | Pricing Methods With Significant Unobservable Market Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value Disclosure	$ 0		$ 0

[1] Represents counterparty netting against level 2 financial assets and liabilities, where a legally enforceable master netting agreement exists between State Street and the counterparty. Netting also reflects asset and liability reductions of $854 million and $367 million, respectively, for cash collateral received from and deposited with derivative counterparties. This netting cannot be disaggregated by type of derivative instrument.