State Street (STT) 10-Q 8 May 15 2015 Q1 Quarterly report Financial data

Document_And_Entity_Informatio

Document And Entity Information	3 Months Ended
	Mar. 31, 2015	Apr. 30, 2015
Document And Entity Information [Abstract]
Entity Registrant Name	STATE STREET Corp
Entity Central Index Key	93751
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Amendment Flag	FALSE
Entity Common Stock, Shares Outstanding		411,679,538

Consolidated_Statement_of_Inco

Consolidated Statement of Income (USD $)	3 Months Ended
In Millions, except Share data in Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Fee revenue:
Servicing fees	$1,273	$1,238
Management fees	301	292
Trading services	324	253
Securities finance	101	85
Processing fees and other	61	56
Total fee revenue	2,060	1,924
Net interest revenue:
Interest revenue	642	655
Interest expense	96	100
Net interest revenue	546	555
Gains (losses) related to investment securities, net:
Net gains (losses) from sales of available-for-sale securities	0	15
Losses from other-than-temporary impairment	-1	-1
Losses reclassified (from) to other comprehensive income	0	-8
Gains (losses) related to investment securities, net	-1	6
Total revenue	2,605	2,485
Provision for loan losses	4	2
Expenses:
Compensation and employee benefits	1,087	1,157
Information systems and communications	247	244
Transaction processing services	197	191
Occupancy	113	114
Acquisition and restructuring costs	6	33
Professional services	96	105
Amortization of other intangible assets	50	54
Other	301	130
Total expenses	2,097	2,028
Income before income tax expense	504	455
Income tax expense	95	92
Net income	409	363
Net income available to common shareholders	$377	$356
Earnings per common share:
Basic (in dollars per share)	$0.91	$0.83
Diluted (in dollars per share)	$0.90	$0.81
Average common shares outstanding (in thousands):
Basic (in shares)	412,225	430,621
Diluted (in shares)	418,750	438,815
Cash dividends declared (in dollars per share)	$0.30	$0.26

Consolidated_Statement_of_Comp

Consolidated Statement of Comprehensive Income (Unaudited) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$409	$363
Other comprehensive income (loss), net of related taxes:
Foreign currency translation, net of related taxes of ($64) and $8, respectively	-699	27
Net unrealized gains (losses) on available-for-sale securities, net of reclassification adjustment and net of related taxes of $123 and $162, respectively	194	259
Net unrealized gains (losses) on available-for-sale securities designated in fair value hedges, net of related taxes of ($10) and ($6), respectively	-15	-10
Other-than-temporary impairment on held-to-maturity securities related to factors other than credit, net of related taxes of $3 and $5, respectively	4	8
Net unrealized gains (losses) on cash flow hedges, net of related taxes of ($8) and ($5), respectively	12	-7
Net unrealized gains on retirement plans, net of related taxes of $4 and $3, respectively	5	6
Other comprehensive income (loss)	-499	283
Total comprehensive income	($90)	$646

Consolidated_Statement_of_Comp1

Consolidated Statement of Comprehensive Income (Unaudited) (Parenthetical) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Foreign currency translation, net of related taxes of	($64)	$8
Change in net unrealized losses on available-for-sale securities, net of reclassification adjustment and net of related taxes of	123	162
Change in net unrealized losses on available-for-sale securities designated in fair value hedges, net of related taxes of	-10	-6
Other-than-temporary impairment on held-to-maturity securities related to factors other than credit, net of related taxes of	3	5
Change in net unrealized losses on cash flow hedges, net of related taxes of	-8	-5
Change in unrealized losses on retirement plans, net of related taxes of	$4	$3

Consolidated_Statement_of_Cond

Consolidated Statement of Condition (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Assets:
Cash and due from banks	$3,149	$1,855
Interest-bearing deposits with banks	83,398	93,523
Securities purchased under resale agreements	11,331	2,390
Trading account assets	1,145	924
Investment securities available for sale	96,612	94,913
Investment securities held to maturity (fair value of $16,417 and $17,842)	16,245	17,723
Loans and leases (less allowance for losses of $41 and $38)	18,278	18,161
Premises and equipment (net of accumulated depreciation of $4,653 and $4,599)	1,933	1,937
Accrued interest and fees receivable	2,281	2,242
Goodwill	5,663	5,826
Other intangible assets	1,892	2,025
Other assets	37,549	32,600
Total assets	279,476	274,119
Deposits:
Noninterest-bearing	72,704	70,490
Interest-bearing—U.S.	30,769	33,012
Interest-bearing—non-U.S.	107,879	105,538
Total deposits	211,352	209,040
Securities sold under repurchase agreements	10,158	8,925
Federal funds purchased	17	21
Other short-term borrowings	4,346	4,381
Accrued expenses and other liabilities	23,610	20,237
Long-term debt	9,174	10,042
Total liabilities	258,657	252,646
Commitments, guarantees and contingencies (notes 7 and 8)
Shareholders’ equity:
Common stock, $1 par: 750,000,000 shares authorized; 503,879,642 and 503,880,120 shares issued	504	504
Surplus	9,744	9,791
Retained earnings	15,135	14,882
Accumulated other comprehensive income (loss)	-1,006	-507
Treasury stock, at cost (92,569,079 and 88,684,969 shares)	-5,519	-5,158
Total shareholders’ equity	20,819	21,473
Total liabilities and shareholders’ equity	279,476	274,119
Series C Preferred Stock
Shareholders’ equity:
Preferred stock, no par: 3,500,000 shares authorized; Series C, 5,000 shares issued and outstanding, Series D, 7,500 shares issued and outstanding, and Series E, 7,500 shares issued and outstanding	491	491
Series D Preferred Stock
Shareholders’ equity:
Preferred stock, no par: 3,500,000 shares authorized; Series C, 5,000 shares issued and outstanding, Series D, 7,500 shares issued and outstanding, and Series E, 7,500 shares issued and outstanding	742	742
Series E Preferred Stock
Shareholders’ equity:
Preferred stock, no par: 3,500,000 shares authorized; Series C, 5,000 shares issued and outstanding, Series D, 7,500 shares issued and outstanding, and Series E, 7,500 shares issued and outstanding	$728	$728

Consolidated_Statement_of_Cond1

Consolidated Statement of Condition (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, except Share data, unless otherwise specified
Current Assets:
Investment securities held to maturity, fair value	$16,417	$17,842
Loans and leases, allowance for losses	41	38
Premises and equipment, accumulated depreciation	$4,653	$4,599
Stockholders' Equity:
Common stock, par value (in dollars per share)	$1	$1
Common stock, shares authorized (in shares)	750,000,000	750,000,000
Common stock, shares issued (in shares)	503,879,642	503,880,120
Preferred stock, shares authorized (in shares)	3,500,000	3,500,000
Treasury stock, shares (in shares)	92,569,079	88,684,969
Series E Preferred Stock
Stockholders' Equity:
Preferred stock, shares issued (in shares)	7,500	0
Preferred stock, shares outstanding (in shares)	7,500	0
Series C Preferred Stock
Stockholders' Equity:
Preferred stock, shares issued (in shares)	5,000	5,000
Preferred stock, shares outstanding (in shares)	5,000	5,000
Series D Preferred Stock
Stockholders' Equity:
Preferred stock, shares issued (in shares)	7,500	0
Preferred stock, shares outstanding (in shares)	7,500	0

Consolidated_Statement_of_Chan

Consolidated Statement of Changes In Shareholders' Equity (USD $)	Total	PREFERRED STOCK	COMMON STOCK	Surplus	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	TREASURY STOCK
In Millions, except Share data in Thousands, unless otherwise specified
Beginning balance at Dec. 31, 2013	$20,378	$491	$504	$9,776	$13,395	($95)	($3,693)
Beginning balance (shares) at Dec. 31, 2013			503,883				69,754
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	363				363
Other comprehensive income (loss)	283					283
Accretion of issuance costs	742	-742
Cash dividends declared:
Common stock dividends	-112				-112
Preferred stock cash dividend	-6				-6
Common stock acquired	-420						-420
Common stock acquired (shares)							6,075
Common stock awards and options exercised, including related taxes	-46			-39			-85
Common stock awards and options exercised, including related taxes (shares)			-2				-2,403
Other	-1				-1
Other (shares)							-14
Ending balance at Mar. 31, 2014	21,273	1,233	504	9,737	13,639	188	-4,028
Ending balance (shares) at Mar. 31, 2014			503,881				73,440
Beginning balance at Dec. 31, 2014	21,473	1,961	504	9,791	14,882	-507	-5,158
Beginning balance (shares) at Dec. 31, 2014			503,880				88,685
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	409				409
Other comprehensive income (loss)	-499					-499
Cash dividends declared:
Common stock dividends	-124				-124
Preferred stock cash dividend	-31				-31
Common stock acquired	-470						-470
Common stock acquired (shares)							6,277
Common stock awards and options exercised, including related taxes	-62			-47			-109
Common stock awards and options exercised, including related taxes (shares)							-2,400
Other	-1				-1
Other (shares)							-7
Ending balance at Mar. 31, 2015	$20,819	$1,961	$504	$9,744	$15,135	($1,006)	($5,519)
Ending balance (shares) at Mar. 31, 2015			503,880				92,569

Consolidated_Statement_of_Chan1

Consolidated Statement of Changes In Shareholders' Equity (Unaudited) (Parenthetical) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Stockholders' Equity [Abstract]
Cash dividends declared (in dollars per share)	$0.30	$0.26
Common stock awards and options exercised, related taxes	$34	$41

Consolidated_Statement_of_Cash

Consolidated Statement of Cash Flows (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Operating Activities:
Net income	$409	$363
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income tax expense	0	-34
Amortization of other intangible assets	50	54
Other non-cash adjustments for depreciation, amortization and accretion, net	135	99
Losses (gains) related to investment securities, net	1	-6
Change in trading account assets, net	-221	-46
Change in accrued interest and fees receivable, net	-39	-74
Change in collateral deposits, net	-3,199	-419
Change in unrealized losses (gains) on foreign exchange derivatives, net	563	267
Change in other assets, net	1,528	34
Change in accrued expenses and other liabilities, net	982	1,542
Other, net	188	126
Net cash provided by operating activities	397	1,906
Investing Activities:
Net decrease (increase) in interest-bearing deposits with banks	10,125	-11,539
Net (increase) decrease in securities purchased under resale agreements	-8,941	143
Proceeds from sales of available-for-sale securities	1,656	1,816
Proceeds from maturities of available-for-sale securities	6,467	8,733
Purchases of available-for-sale securities	-10,979	-10,377
Proceeds from maturities of available-for-sale securities	993	669
Purchases of held-to-maturity securities	-2	-1,157
Net increase in loans	-111	-2,628
Purchases of equity investments and other long-term assets	-114	-82
Purchases of premises and equipment	-96	-110
Other, net	11	18
Net cash used in investing activities	-991	-14,514
Financing Activities:
Net decrease in time deposits	-2,224	-1,084
Net increase in all other deposits	4,536	13,464
Net increase in short-term borrowings	1,194	1,030
Payments for long-term debt and obligations under capital leases	-915	-257
Proceeds from issuance of preferred stock	0	742
Proceeds from exercises of common stock options	4	9
Purchases of common stock	-470	-420
Excess tax benefit related to stock-based compensation	34	41
Repurchases of common stock for employee tax withholding	-115	-140
Payments for cash dividends	-156	-120
Net cash provided by financing activities	1,888	13,265
Net increase	1,294	657
Cash and due from banks at beginning of period	1,855	3,220
Cash and due from banks at end of period	$3,149	$3,877

Basis_of_Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies
	The accounting and financial reporting policies of State Street Corporation conform to U.S. generally accepted accounting principles, referred to as GAAP. State Street Corporation, the parent company, is a financial holding company headquartered in Boston, Massachusetts. Unless otherwise indicated or unless the context requires otherwise, all references in these notes to consolidated financial statements to “State Street,” “we,” “us,” “our” or similar references mean State Street Corporation and its subsidiaries on a consolidated basis. Our principal banking subsidiary is State Street Bank and Trust Company, or State Street Bank.
	The accompanying Consolidated Financial Statements should be read in conjunction with the financial and risk factor information included in our 2014 Annual Report on Form 10-K (2014 Form 10-K), which we previously filed with the Securities and Exchange Commission, or SEC.
	The consolidated financial statements accompanying these condensed notes are unaudited. In the opinion of management, all adjustments, consisting only of normal recurring adjustments, which are necessary for a fair statement of the consolidated results of operations in these financial statements, have been made. Certain previously reported amounts presented in this Form 10-Q have been reclassified to conform to current-period presentation. Events occurring subsequent to the date of our consolidated statement of condition were evaluated for potential recognition or disclosure in our consolidated financial statements through the date we filed this Form 10-Q with the SEC.
	The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions in the application of certain of our significant accounting policies that may materially affect the reported amounts of assets, liabilities, equity, revenue, and expenses. As a result of unanticipated events or circumstances, actual results could differ from those estimates. These accounting estimates reflect the best judgment of management, but actual results could differ.
	Our consolidated statement of condition as of December 31, 2014 included in the accompanying consolidated financial statements was derived from the audited financial statements as of that date, but does not include all notes required by GAAP for a complete set of consolidated financial statements.
	Recent Accounting Developments:
	In February 2015, the Financial Accounting Standards Board, or FASB, issued an amendment to GAAP to remove the concept of "extraordinary items," which are defined as items that are unusual and infrequent in nature. The amendment, which allows for early adoption, is effective for State Street beginning on January 1, 2016. Our adoption of this amendment is not expected to have a material effect on our consolidated financial statements.
	In February 2015, the FASB issued an amendment to GAAP that updates the consolidation model used to evaluate whether a legal entity is required to be consolidated. The amendment, which allows for early adoption, is effective for State Street beginning on January 1, 2016, and may be applied retrospectively or via a modified retrospective approach. We are currently assessing the potential impact of this amendment on our consolidated financial statements.
	In April 2015, the FASB issued an amendment to GAAP that requires debt issuance costs to be presented in the consolidated balance sheet as a direct deduction from the carrying value of the associated debt liability, consistent with the presentation of a debt discount. The amendment, which allows for early adoption, is effective for State Street beginning on January 1, 2016. Our debt issuance costs that are currently classified as deferred credits and have a balance of approximately $28 million as of March 31, 2015 will be reclassified as contra liabilities upon adoption.
	In April 2015, the FASB issued an amendment to GAAP which will assist entities in evaluating the accounting for fees paid by a customer in a cloud computing arrangement. The amendment, which allows for early adoption, is effective for State Street beginning on January 1, 2016. Our adoption of this amendment is not expected to have a material effect on our consolidated financial statements.

Fair_Value

Fair Value	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value	Fair Value
	Fair-Value Measurements:
	We carry trading account assets, investment securities available for sale and various types of derivative financial instruments at fair value in our consolidated statement of condition on a recurring basis. Changes in the fair values of these financial assets and liabilities are recorded either as components of our consolidated statement of income or as components of accumulated other comprehensive income, or AOCI, within shareholders' equity in our consolidated statement of condition.
	We measure fair value for the above-described financial assets and liabilities in conformity with GAAP that governs the measurement of the fair value of financial instruments. Management believes that its valuation techniques and underlying assumptions used to measure fair value conform to the provisions of GAAP. We categorize the financial assets and liabilities that we carry at fair value based on a prescribed three-level valuation hierarchy. For information about our valuation techniques for financial assets and financial liabilities measured at fair value and the fair value hierarchy, refer to note 2 to the consolidated financial statements on pages 130 to 141 of the 2014 Form 10-K.
	The following tables present information with respect to our financial assets and liabilities carried at fair value in our consolidated statement of condition on a recurring basis as of the dates indicated. No transfers of financial assets or liabilities between levels 1 and 2 occurred in the three months ended March 31, 2015 or the year ended December 31, 2014.
		Fair-Value Measurements on a Recurring Basis
		as of March 31, 2015
	(In millions)	Quoted Market			Pricing Methods			Pricing Methods				Impact of Netting(1)			Total Net
		Prices in Active			with Significant			with Significant							Carrying Value
		Markets			Observable			Unobservable							in Consolidated
		(Level 1)			Market Inputs			Market Inputs							Statement of
					(Level 2)			(Level 3)							Condition
	Assets:
	Trading account assets:
	U.S. government securities	$	20		$	—		$	—						$	20
	Non-U.S. government securities	569			—			—							569
	Other	20			536			—							556
	Total trading account assets	609			536			—							1,145
	Investment securities available for sale:
	U.S. Treasury and federal agencies:
	Direct obligations	12,418			578			—							12,996
	Mortgage-backed securities	—			21,046			—							21,046
	Asset-backed securities:
	Student loans	—			11,807			257							12,064
	Credit cards	—			2,917			—							2,917
	Sub-prime	—			911			—							911
	Other(2)	—			395			3,633							4,028
	Total asset-backed securities	—			16,030			3,890							19,920
	Non-U.S. debt securities:
	Mortgage-backed securities	—			8,621			43							8,664
	Asset-backed securities	—			3,133			228							3,361
	Government securities	—			3,811			—							3,811
	Other(3)	—			4,789			442							5,231
	Total non-U.S. debt securities	—			20,354			713							21,067
	State and political subdivisions	—			11,012			37							11,049
	Collateralized mortgage obligations	—			5,308			522							5,830
	Other U.S. debt securities	—			4,064			9							4,073
	U.S. equity securities	—			39			—							39
	Non-U.S. equity securities	—			2			—							2
	U.S. money-market mutual funds	—			582			—							582
	Non-U.S. money-market mutual funds	—			8			—							8
	Total investment securities available for sale	12,418			79,023			5,171							96,612
	Other assets:
	Derivative instruments:
	Foreign exchange contracts	—			15,931			185				$	(8,087	)	8,029
	Interest-rate contracts	—			141			—				(123		)	18
	Other derivative contracts	—			3			—				(2		)	1
	Total derivative instruments	—			16,075			185				(8,212		)	8,048
	Total assets carried at fair value	$	13,027		$	95,634		$	5,356			$	(8,212	)	$	105,805
	Liabilities:
	Accrued expenses and other liabilities:
	Trading account liabilities:
	Other	$	4		$	—		$	—			$	—		$	4
	Derivative instruments:
	Foreign exchange contracts	—			16,881			172				(10,361		)	6,692
	Interest-rate contracts	—			232			—				(44		)	188
	Other derivative contracts	—			103			9				(2		)	110
	Total derivative instruments	—			17,216			181				(10,407		)	6,990
	Total liabilities carried at fair value	$	4		$	17,216		$	181			$	(10,407	)	$	6,994
	(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 $466 million and $2.66 billion, respectively, for cash collateral received from and provided to derivative counterparties.
	(2) As of March 31, 2015 the fair value of other asset-backed securities was primarily composed of $3.6 billion of collateralized loan obligations and approximately $348 million of automobile loan securities.
	(3) As of March 31, 2015 the fair value of other non-U.S. debt securities was primarily composed of $3.3 billion of covered bonds and $1.1 billion of corporate bonds.
		Fair-Value Measurements on a Recurring Basis
		as of December 31, 2014
(In millions)	Quoted Market			Pricing Methods			Pricing Methods				Impact of Netting(1)			Total Net
	Prices in Active			with Significant			with Significant							Carrying Value
	Markets			Observable			Unobservable							in Consolidated
	(Level 1)			Market Inputs			Market Inputs							Statement of
				(Level 2)			(Level 3)							Condition
Assets:
Trading account assets:
U.S. government securities	$	20		$	—		$	—						$	20
Non-U.S. government securities	378			—			—							378
Other	20			506			—							526
Total trading account assets	418			506			—							924
Investment securities available for sale:
U.S. Treasury and federal agencies:
Direct obligations	10,056			599			—							10,655
Mortgage-backed securities	—			20,714			—							20,714
Asset-backed securities:
Student loans	—			12,201			259							12,460
Credit cards	—			3,053			—							3,053
Sub-prime	—			951			—							951
Other(2)	—			365			3,780							4,145
Total asset-backed securities	—			16,570			4,039							20,609
Non-U.S. debt securities:
Mortgage-backed securities	—			9,606			—							9,606
Asset-backed securities	—			2,931			295							3,226
Government securities	—			3,909			—							3,909
Other(3)	—			5,057			371							5,428
Total non-U.S. debt securities	—			21,503			666							22,169
State and political subdivisions	—			10,782			38							10,820
Collateralized mortgage obligations	—			4,725			614							5,339
Other U.S. debt securities	—			4,100			9							4,109
U.S. equity securities	—			39			—							39
Non-U.S. equity securities	—			2			—							2
U.S. money-market mutual funds	—			449			—							449
Non-U.S. money-market mutual funds	—			8			—							8
Total investment securities available for sale	10,056			79,491			5,366							94,913
Other assets:
Derivatives instruments:
Foreign exchange contracts	—			15,054			81				$	(7,211	)	7,924
Interest-rate contracts	—			77			—				(68		)	9
Other derivative contracts	—			2			—				(1		)	1
Total derivative instruments	—			15,133			81				(7,280		)	7,934
Total assets carried at fair value	$	10,474		$	95,130		$	5,447			$	(7,280	)	$	103,771
Liabilities:
Accrued expenses and other liabilities:
Derivative instruments:
Foreign exchange contracts	$	—		$	14,851		$	74			$	(8,879	)	$	6,046
Interest-rate contracts	—			239			—				(46		)	193
Other derivative contracts	—			61			9				(1		)	69
Total derivative instruments	—			15,151			83				(8,926		)	6,308
Total liabilities carried at fair value	$	—		$	15,151		$	83			$	(8,926	)	$	6,308
(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 $983 million and $2.63 billion, respectively, for cash collateral received from and provided to derivative counterparties.
(2) As of December 31, 2014, the fair value of other asset-backed securities was primarily composed of $3.8 billion of collateralized loan obligations and approximately $315 million of automobile loan securities.
(3) As of December 31, 2014, the fair value of other non-U.S. debt securities was primarily composed of $3.3 billion of covered bonds and $1.2 billion of corporate bonds.
The following tables present activity related to our level-3 financial assets and liabilities during the three months ended March 31, 2015 and 2014, respectively. Transfers into and out of level 3 are reported as of the beginning of the period presented. In the three months ended March 31, 2015 and 2014, transfers out of level 3 were mainly related to certain mortgage- and asset-backed securities, including non-U.S. debt securities, for which fair value was measured using prices for which observable market information became available.
	Fair Value Measurements Using Significant Unobservable Inputs
	Three Months Ended March 31, 2015
	Fair Value  as of			Total Realized and							Purchases			Settlements			Transfers			Fair Value  as of			Change in
	31-Dec-14			Unrealized Gains (Losses)													out of			March 31, 2015(1)			Unrealized
																	Level 3						Gains
																							(Losses)
																							Related to
																							Financial
																							Instruments
																							Held as of
																							March 31,
(In millions)				Recorded			Recorded																2015
				in			in Other
				Revenue			Comprehensive
							Income
Assets:
Investment securities available for sale:
Asset-backed securities:
Student loans	$	259		$	—		$	1			$	—		$	(3	)	$	—		$	257
Other	3,780			12			(12		)		—			(147		)	—			3,633
Total asset-backed securities	4,039			12			(11		)		—			(150		)	—			3,890
Non-U.S. debt securities:
Mortgage-backed securities	—			—			—				43			—			—			43
Asset-backed securities	295			1			—				—			(68		)	—			228
Other	371			—			1				111			(41		)	—			442
Total non-U.S. debt securities	666			1			1				154			(109		)	—			713
State and political subdivisions	38			—			(1		)		—			—			—			37
Collateralized mortgage obligations	614			—			—				293			(36		)	(349		)	522
Other U.S. debt securities	9			—			—				—			—			—			9
Total investment securities available for sale	5,366			13			(11		)		447			(295		)	(349		)	5,171
Other assets:
Derivative instruments:
Derivative instruments, Foreign exchange contracts	81			131			—				36			(63		)	—			185			$	107
Total derivative instruments	81			131			—				36			(63		)	—			185			107
Total assets carried at fair value	$	5,447		$	144		$	(11	)		$	483		$	(358	)	$	(349	)	$	5,356		$	107
	Fair-Value Measurements Using Significant Unobservable Inputs
	Three Months Ended March 31, 2015
	Fair Value  as of			Total Realized and			Issuances				Settlements			Fair Value  as of			Change in
	31-Dec-14			Unrealized (Gains) Losses										March 31, 2015(2)			Unrealized
																	(Gains)
																	Losses Related to
																	Financial
																	Instruments
																	Held as of
																	March 31,
(In millions)				Recorded													2015
				in
				Revenue
Liabilities:
Accrued expenses and other liabilities:
Derivative instruments:
Foreign exchange contracts	$	74		$	109		$	37			$	(48	)	$	172		$	93
Other	9			—			—				—			9
Total derivative instruments	83			109			37				(48		)	181			93
Total liabilities carried at fair value	$	83		$	109		$	37			$	(48	)	$	181		$	93
(1) There were no transfers of assets into level 3 during the three months ended March 31, 2015.
(2) There were no transfers of liabilities into or out of level 3 during the three months ended March 31, 2015.
	Fair-Value Measurements Using Significant Unobservable Inputs
	Three Months Ended March 31, 2014
	Fair Value  as of December 31,			Total Realized and							Purchases			Sales			Settlements			Transfers			Fair Value  as of		Change in
	2013			Unrealized Gains (Losses)																out of			March 31, 2014(1)		Unrealized
																				Level 3					Gains
																									(Losses)
																									Related to
																									Financial
																									Instruments
																									Held as of
																									March 31,
(In millions)				Recorded			Recorded																		2014
				in			in Other
				Revenue			Comprehensive
							Income
Assets:
Investment securities available for sale:
U.S. Treasury and federal agencies, mortgage-backed securities	$	716		$	—		$	—			$	—		$	—		$	(5	)	$	(611	)	$	100
Asset-backed securities:
Student loans	423			1			1				—			—			(13		)	(79		)	333
Credit cards	24			—			—				—			—			(24		)	—			—
Other	4,532			15			(4		)		6			—			(245		)	—			4,304
Total asset-backed securities	4,979			16			(3		)		6			—			(282		)	(79		)	4,637
Non-U.S. debt securities:
Mortgage-backed securities	375			—			—				—			—			—			(375		)	—
Asset-backed securities	798			2			(1		)		—			—			(63		)	(124		)	612
Other	464			—			(1		)		—			(1		)	—			—			462
Total non-U.S. debt securities	1,637			2			(2		)		—			(1		)	(63		)	(499		)	1,074
State and political subdivisions	43			—			—				—			—			(1		)	—			42
Collateralized mortgage obligations	162			—			—				80			(6		)	(6		)	(28		)	202
Other U.S. debt securities	8			—			—				—			—			—			—			8
Total investment securities available for sale	7,545			18			(5		)		86			(7		)	(357		)	(1,217		)	6,063
Other assets:
Derivative instruments:
Derivative instruments, Foreign exchange contracts	19			(11		)	—				7			—			(9		)	—			6		$	(7	)
Total derivative instruments	19			(11		)	—				7			—			(9		)	—			6		(7		)
Total assets carried at fair value	$	7,564		$	7		$	(5	)		$	93		$	(7	)	$	(366	)	$	(1,217	)	$	6,069	$	(7	)
	Fair-Value Measurements Using Significant Unobservable Inputs
	Three Months Ended March 31, 2014
	Fair Value  as of December 31,			Total Realized and			Issuances				Settlements			Fair Value  as of			Change in
	2013			Unrealized (Gains) Losses										March 31, 2014(2)			Unrealized
																	(Gains)
																	Losses
																	Related to
																	Financial
																	Instruments
																	Held as of
																	March 31,
(In millions)				Recorded													2014
				in
				Revenue
Liabilities:
Accrued expenses and other liabilities:
Derivative instruments:
Foreign exchange contracts	$	17		$	(10	)	$	7			$	(6	)	$	8		$	(5	)
Other	9			—			—				—			9			—
Total derivative instruments	26			(10		)	7				(6		)	17			(5		)
Total liabilities carried at fair value	$	26		$	(10	)	$	7			$	(6	)	$	17		$	(5	)
(1) There were no transfers of assets into level 3 during the three months ended March 31, 2014.
(2) There were no transfers of liabilities into or out of level 3 in the three months ended March 31, 2014.
The following table presents total realized and unrealized gains and losses for our level-3 financial assets and liabilities and where they are presented in our consolidated statement of income for the periods indicated:
	Three Months Ended March 31,
	Total Realized and						Change in
	Unrealized Gains						Unrealized Gains
	(Losses) Recorded						(Losses) Related to
	in Revenue						Financial
							Instruments Held as of
							March 31,
(In millions)	2015			2014			2015				2014
Fee revenue:
Trading services	$	22		$	(1	)	$	14			$	(2	)
Total fee revenue	22			(1		)	14				(2		)
Net interest revenue	13			18			—				—
Total revenue	$	35		$	17		$	14			$	(2	)
The following table presents quantitative information, as of the dates indicated, about the valuation techniques and significant unobservable inputs used in the valuation of our level-3 financial assets and liabilities measured at fair value on a recurring basis for which we use internally-developed pricing models. The significant unobservable inputs for our level-3 financial assets and liabilities whose fair value is measured using pricing information from non-binding broker or dealer quotes are not included in the table, as the specific inputs applied are not provided by the broker/dealer.
		Quantitative Information about Level-3 Fair-Value Measurements
		Fair Value										Weighted-Average
(Dollars in millions)		As of March 31, 2015			As of December 31, 2014			Valuation Technique		Significant		As of March 31, 2015		As of December 31, 2014
										Unobservable Input(1)
Significant unobservable inputs readily available to State Street:
Assets:
Asset-backed securities, other		$	54		$	59		Discounted cash flows		Credit spread		0.2	%	0.2	%
State and political subdivisions		37			38			Discounted cash flows		Credit spread		2.2		2.1
Derivative instruments, foreign exchange contracts		185			81			Option model		Volatility		10.8		9.1
Total		$	276		$	178
Liabilities:
Derivative instruments, foreign exchange contracts		$	172		$	74		Option model		Volatility		11.3		9
Derivative instruments, other(2)		9			9			Discounted cash flows		Participant redemptions		5		5.2
Total		$	181		$	83
(1) Significant changes in these unobservable inputs would result in significant changes in fair value measure.
(2) Relates to stable value wrap contracts; refer to the sensitivity discussion following the tables presented below, and to note 7.
We use internally-developed pricing models to measure the fair value of our level-3 financial assets and liabilities, which models incorporate discounted cash flow and option modeling techniques. Use of these techniques requires the determination of
relevant inputs and assumptions, some of which represent significant unobservable inputs as indicated in the following table. Accordingly, changes in these unobservable inputs may have a significant impact on fair value.
The following tables present information with respect to the composition of our level-3 financial assets and liabilities, by availability of significant unobservable inputs, as of the dates indicated:
31-Mar-15		Significant Unobservable Inputs Readily Available to State Street(1)			Significant Unobservable Inputs Not Developed by State Street and Not Readily Available(2)			Total Assets and Liabilities with Significant Unobservable Inputs
(In millions)
Assets:
Asset-backed securities, student loans		$	—		$	257		$	257
Asset-backed securities, other		54			3,579			3,633
Non-U.S. debt securities, mortgage-backed securities		—			43			43
Non-U.S. debt securities, asset-backed securities		—			228			228
Non-U.S. debt securities, other					442			442
State and political subdivisions		37			—			37
Collateralized mortgage obligations		—			522			522
Other U.S. debt securities		—			9			9
Derivative instruments, foreign exchange contracts		185			—			185
Total		$	276		$	5,080		$	5,356
Liabilities:
Derivative instruments, foreign exchange contracts		$	172		$	—		$	172
Derivative instruments, other		9			—			9
Total		$	181		$	—		$	181
(1) Information with respect to these model-priced financial assets and liabilities is provided above in a separate table.
(2) Fair value for these financial assets is measured using non-binding broker or dealer quotes.
31-Dec-14		Significant Unobservable Inputs Readily Available to State Street(1)			Significant Unobservable Inputs Not Developed by State Street and Not Readily Available(2)			Total Assets and Liabilities with Significant Unobservable Inputs
(In millions)
Assets:
Asset-backed securities, student loans		$	—		$	259		$	259
Asset-backed securities, other		59			3,721			3,780
Non-U.S. debt securities, asset-backed securities		—			295			295
Non-U.S. debt securities, other		—			371			371
State and political subdivisions		38			—			38
Collateralized mortgage obligations		—			614			614
Other U.S. debt securities		—			9			9
Derivative instruments, foreign exchange contracts		81			—			81
Total		$	178		$	5,269		$	5,447
Liabilities:
Derivative instruments, foreign exchange contracts		$	74		$	—		$	74
Derivative instruments, other		9			—			9
Total		$	83		$	—		$	83
(1) Information with respect to these model-priced financial assets and liabilities is provided above in a separate table.
(2) Fair value for these financial assets is measured using non-binding broker or dealer quotes.
Fair Value Estimates:
Estimates of fair value for financial instruments not carried at fair value on a recurring basis in our consolidated statement of condition are generally subjective in nature, and are determined as of a
specific point in time based on the characteristics of the financial instruments and relevant market information.
The following tables present the reported amounts and estimated fair values of the financial assets and liabilities not carried at fair value on a recurring basis, as they would be categorized within the fair-value hierarchy, as of the dates indicated.
								Fair-Value Hierarchy
31-Mar-15		Reported Amount			Estimated Fair Value			Quoted Market Prices in Active Markets (Level 1)				Pricing Methods with Significant Observable Market Inputs (Level 2)			Pricing Methods with Significant Unobservable Market Inputs (Level 3)
(In millions)
Financial Assets:
Cash and due from banks		$	3,149		$	3,149		$	3,149			$	—		$	—
Interest-bearing deposits with banks		83,398			83,398			—				83,398			—
Securities purchased under resale agreements		11,331			11,331			—				11,331			—
Investment securities held to maturity		16,245			16,417			—				16,417			—
Net loans (excluding leases)		17,344			17,339			—				17,177			162
Financial Liabilities:
Deposits:
Noninterest-bearing		$	72,704		$	72,704		$	—			$	72,704		$	—
Interest-bearing - U.S.		30,769			30,769			—				30,769			—
Interest-bearing - non-U.S.		107,879			107,879			—				107,879			—
Securities sold under repurchase agreements		10,158			10,158			—				10,158			—
Federal funds purchased		17			17			—				17			—
Other short-term borrowings		4,346			4,346			—				4,346			—
Long-term debt		9,174			9,432			—				8,592			840
								Fair-Value Hierarchy
31-Dec-14		Reported Amount			Estimated Fair Value			Quoted Market Prices in Active Markets (Level 1)				Pricing Methods with Significant Observable Market Inputs (Level 2)			Pricing Methods with Significant Unobservable Market Inputs (Level 3)
(In millions)
Financial Assets:
Cash and due from banks		$	1,855		$	1,855		$	1,855			$	—		$	—
Interest-bearing deposits with banks		93,523			93,523			—				93,523			—
Securities purchased under resale agreements		2,390			2,390			—				2,390			—
Investment securities held to maturity		17,723			17,842			—				17,842			—
Net loans (excluding leases)		17,158			17,131			—				16,964			167
Financial Liabilities:
Deposits:
Noninterest-bearing		$	70,490		$	70,490		$	—			$	70,490		$	—
Interest-bearing - U.S.		33,012			33,012			—				33,012			—
Interest-bearing - non-U.S.		105,538			105,538			—				105,538			—
Securities sold under repurchase agreements		8,925			8,925			—				8,925			—
Federal funds purchased		21			21			—				21			—
Other short-term borrowings		4,381			4,381			—				4,381			—
Long-term debt		10,042			10,229			—				9,382			847

Investment_Securities

Investment Securities	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Investment Securities	Investment Securities
	Investment securities held by us are classified as either trading, available-for-sale or held-to-maturity at the time of purchase and reassessed periodically, based on management’s intent.
	Generally, trading assets are debt and equity securities purchased in connection with our trading activities and, as such, are expected to be sold in the near term. Our trading activities typically involve active and frequent buying and selling with the objective of generating profits on short-term movements. Securities available-for-sale are those securities that we intend to hold for an indefinite period of time. Available-for-sale securities include securities utilized as part of our asset-and-liability management activities that may be sold in response to changes in interest rates, prepayment risk, liquidity needs or other factors. Securities held to maturity are debt securities that management has the intent and the ability to hold to maturity.
	Trading assets are carried at fair value. Both realized and unrealized gains and losses on trading assets are recorded in trading services revenue in our consolidated statement of income. Debt and marketable equity securities classified as available for sale are carried at fair value, and after-tax net unrealized gains and losses are recorded in AOCI. Gains or losses realized on sales of available-for-sale securities are computed using the specific identification method and are recorded in gains (losses) related to investment securities, net, in our consolidated statement of income. Securities held to maturity are carried at cost, adjusted for amortization of premiums and accretion of discounts.
	The following table presents the amortized cost and fair value, and associated unrealized gains and losses, of investment securities as of the dates indicated:
		March 31, 2015										December 31, 2014
		Amortized			Gross					Fair		Amortized		Gross				Fair
		Cost			Unrealized					Value		Cost		Unrealized				Value
	(In millions)				Gains			Losses						Gains		Losses
	Available for sale:
	U.S. Treasury and federal agencies:
	Direct obligations	$	12,803		$	194		$	1	$	12,996	$	10,573	$	83	$	1	$	10,655
	Mortgage-backed securities	20,861			251			66		21,046		20,648		193		127		20,714
	Asset-backed securities:
	Student loans(1)	12,070			107			113		12,064		12,478		106		124		12,460
	Credit cards	2,941			10			34		2,917		3,077		10		34		3,053
	Sub-prime	961			2			52		911		1,005		2		56		951
	Other(2)	3,950			90			12		4,028		4,055		100		10		4,145
	Total asset-backed securities	19,922			209			211		19,920		20,615		218		224		20,609
	Non-U.S. debt securities:
	Mortgage-backed securities	8,522			146			4		8,664		9,442		168		4		9,606
	Asset-backed securities	3,353			9			1		3,361		3,215		11		—		3,226
	Government securities	3,800			11			—		3,811		3,899		10		—		3,909
	Other(3)	5,186			50			5		5,231		5,383		52		7		5,428
	Total non-U.S. debt securities	20,861			216			10		21,067		21,939		241		11		22,169
	State and political subdivisions	10,729			357			37		11,049		10,532		325		37		10,820
	Collateralized mortgage obligations	5,738			99			7		5,830		5,280		71		12		5,339
	Other U.S. debt securities	3,987			94			8		4,073		4,033		88		12		4,109
	U.S. equity securities	31			9			1		39		29		10		—		39
	Non-U.S. equity securities	2			—			—		2		2		—		—		2
	U.S. money-market mutual funds	582			—			—		582		449		—		—		449
	Non-U.S. money-market mutual funds	8			—			—		8		8		—		—		8
	Total	$	95,524		$	1,429		$	341	$	96,612	$	94,108	$	1,229	$	424	$	94,913
	Held to maturity:
	U.S. Treasury and federal agencies:
	Direct obligations	$	5,112		$	—		$	69	$	5,043	$	5,114	$	—	$	147	$	4,967
	Mortgage-backed securities	57			4			—		61		62		4		—		66
	Asset-backed securities:
	Student loans(1)	1,755			3			5		1,753		1,814		2		4		1,812
	Credit cards	897			2			—		899		897		2		—		899
	Other	545			3			—		548		577		3		1		579
	Total asset-backed securities	3,197			8			5		3,200		3,288		7		5		3,290
	Non-U.S. debt securities:
	Mortgage-backed securities	3,275			154			19		3,410		3,787		177		22		3,942
	Asset-backed securities	2,298			11			—		2,309		2,868		14		1		2,881
	Government securities	148			—			—		148		154		—		—		154
	Other	65			—			—		65		72		—		—		72
	Total non-U.S. debt securities	5,786			165			19		5,932		6,881		191		23		7,049
	State and political subdivisions	3			—			—		3		9		—		—		9
	Collateralized mortgage obligations	2,090			96			8		2,178		2,369		107		15		2,461
	Total	$	16,245		$	273		$	101	$	16,417	$	17,723	$	309	$	190	$	17,842
	(1) Substantially composed of securities guaranteed by the federal government with respect to at least 97% of defaulted principal and accrued interest on the underlying loans.
	(2) As of March 31, 2015 and December 31, 2014, the fair value of other asset-backed securities was primarily composed of $3.6 billion and $3.8 billion, respectively, of collateralized loan obligations and approximately $348 million and approximately $315 million, respectively, of automobile loan securities.
	(3) As of both March 31, 2015 and December 31, 2014, the fair value of other non-U.S. debt securities was primarily composed of $3.3 billion of covered bonds and $1.1 billion and $1.2 billion, as of March 31, 2015 and December 31, 2014, respectively, of corporate bonds.
	Aggregate investment securities with carrying values of $43.00 billion and $44.02 billion as of March 31, 2015 and December 31, 2014, respectively, were designated as pledged for public and trust deposits, short-term borrowings and for other purposes as provided by law.
	The following tables present the aggregate fair values of investment securities that have been in a continuous unrealized loss position for less than 12 months, and those that have been in a continuous unrealized loss position for 12 months or longer, as of the dates indicated:
		Less than 12 months						12 months or longer				Total
	March 31, 2015	Fair			Gross			Fair		Gross		Fair		Gross
		Value			Unrealized			Value		Unrealized		Value		Unrealized
	(In millions)				Losses					Losses				Losses
	Available for sale:
	U.S. Treasury and federal agencies:
	Direct obligations	$	—		$	—		$	158	$	1	$	158	$	1
	Mortgage-backed securities	1,565			8			4,373		58		5,938		66
Asset-backed securities:
Student loans	1,440			13			4,875		100		6,315		113
Credit cards	—			—			1,287		34		1,287		34
Sub-prime	—			—			860		52		860		52
Other	844			5			640		7		1,484		12
Total asset-backed securities	2,284			18			7,662		193		9,946		211
Non-U.S. debt securities:
Mortgage-backed securities	1,097			3			146		1		1,243		4
Asset-backed securities	499			1			—		—		499		1
Other	641			2			293		3		934		5
Total non-U.S. debt securities	2,237			6			439		4		2,676		10
State and political subdivisions	980			6			776		31		1,756		37
Collateralized mortgage obligations	747			2			208		5		955		7
Other U.S. debt securities	—			—			146		8		146		8
U.S. equity securities	6			1			—		—		6		1
Total	$	7,819		$	41		$	13,762	$	300	$	21,581	$	341
Held to maturity:
U.S. Treasury and federal agencies:
Direct obligations	$	2,062		$	13		$	2,981	$	56	$	5,043	$	69
Asset-backed securities:
Student loans	631			3			232		2		863		5
Total asset-backed securities	631			3			232		2		863		5
Non-U.S. mortgage-backed securities:
Mortgage-backed securities	517			2			569		17		1,086		19
Total non-U.S. debt securities	517			2			569		17		1,086		19
Collateralized mortgage obligations	272			3			415		5		687		8
Total	$	3,482		$	21		$	4,197	$	80	$	7,679	$	101
	Less than 12 months						12 months or longer				Total
December 31, 2014	Fair			Gross			Fair		Gross		Fair		Gross
	Value			Unrealized			Value		Unrealized		Value		Unrealized
(In millions)				Losses					Losses				Losses
Available for sale:
U.S. Treasury and federal agencies:
Direct obligations	$	—		$	—		$	167	$	1	$	167	$	1
Mortgage-backed securities	2,569			9			6,466		118		9,035		127
Asset-backed securities:
Student loans	1,473			15			5,025		109		6,498		124
Credit cards	344			1			1,270		33		1,614		34
Sub-prime	—			—			896		56		896		56
Other	547			1			791		9		1,338		10
Total asset-backed securities	2,364			17			7,982		207		10,346		224
Non-U.S. debt securities:
Mortgage-backed securities	1,350			2			170		2		1,520		4
Other	581			4			328		3		909		7
Total non-U.S. debt securities	1,931			6			498		5		2,429		11
State and political subdivisions	610			3			1,315		34		1,925		37
Collateralized mortgage obligations	731			2			311		10		1,042		12
Other U.S. debt securities	327			2			244		10		571		12
Total	$	8,532		$	39		$	16,983	$	385	$	25,515	$	424
Held to maturity:
U.S. Treasury and federal agencies:
Direct obligations	$	76		$	1		$	4,891	$	146	$	4,967	$	147
Asset-backed securities:
Student Loans	780			3			192		1		972		4
Other	124			1			—		—		124		1
Total asset-backed securities	904			4			192		1		1,096		5
Non-U.S. debt securities:
Mortgage-backed securities	507			3			590		19		1,097		22
Asset-backed securities	699			1			—		—		699		1
Total non-U.S. debt securities	1,206			4			590		19		1,796		23
Collateralized mortgage obligations	422			4			547		11		969		15
Total	$	2,608		$	13		$	6,220	$	177	$	8,828	$	190
The following table presents contractual maturities of debt investment securities as of March 31, 2015:
(In millions)	Under 1			1 to 5			6 to 10		Over 10
	Year			Years			Years		Years
Available for sale:
U.S. Treasury and federal agencies:
Direct obligations	$	1		$	9,246		$	3,238	$	511
Mortgage-backed securities	117			2,420			4,056		14,453
Asset-backed securities:
Student loans	553			5,858			3,816		1,837
Credit cards	227			1,565			1,125		—
Sub-prime	8			7			—		896
Other	170			941			1,398		1,519
Total asset-backed securities	958			8,371			6,339		4,252
Non-U.S. debt securities:
Mortgage-backed securities	1,661			3,511			513		2,979
Asset-backed securities	390			2,796			112		63
Government securities	2,236			1,575			—		—
Other	1,340			3,152			739		—
Total non-U.S. debt securities	5,627			11,034			1,364		3,042
State and political subdivisions	723			2,848			4,952		2,526
Collateralized mortgage obligations	249			1,044			1,077		3,460
Other U.S. debt securities	1,087			2,674			277		35
Total	$	8,762		$	37,637		$	21,303	$	28,279
Held to maturity:
U.S. Treasury and federal agencies:
Direct obligations	$	—		$	—		$	4,999	$	113
Mortgage-backed securities	—			11			11		35
Asset-backed securities:
Student loans	4			182			357		1,212
Credit cards	—			375			522		—
Other	9			370			162		4
Total asset-backed securities	13			927			1,041		1,216
Non-U.S. debt securities:
Mortgage-backed securities	476			939			133		1,727
Asset-backed securities	132			1,993			173		—
Government securities	148			—			—		—
Other	—			65			—		—
Total non-U.S. debt securities	756			2,997			306		1,727
State and political subdivisions	3			—			—		—
Collateralized mortgage obligations	483			290			496		821
Total	$	1,255		$	4,225		$	6,853	$	3,912
The maturities of asset-backed securities, mortgage-backed securities, and collateralized mortgage obligations are based on expected principal payments.
The following tables present gross realized gains and losses from sales of available-for-sale securities, and the components of net impairment losses included in net gains and losses related to investment securities, for the periods indicated:
	Three Months Ended March 31,
(In millions)	2015			2014
Gross realized gains from sales of available-for-sale securities	$	—		$	15
Gross realized losses from sales of available-for-sale securities	—			—
Net impairment losses:
Gross losses from other-than-temporary impairment	(1		)	(1		)
Losses reclassified (from) to other comprehensive income, or OCI	—			(8		)
Net impairment losses(1)	(1		)	(9		)
Gains related to investment securities, net	$	(1	)	$	6
(1) Net impairment losses, recognized in our consolidated statement of income, were composed of the following:
Impairment associated with expected credit losses	$	—		$	(9	)
Impairment associated with management's intent to sell impaired securities prior to recovery in value	—			—
Impairment associated with adverse changes in timing of expected future cash flows	(1		)	—
Net impairment losses	$	(1	)	$	(9	)
The following table presents a roll-forward with respect to net impairment losses that have been recognized in income for the periods indicated:
	Three Months Ended March 31,
(In millions)	2015			2014
Balance, beginning of period	$	115		$	122
Additions:
Losses for which other-than-temporary impairment was not previously recognized	—			9
Losses for which other-than-temporary impairment was previously recognized	1			—
Reductions:
Previously recognized losses related to securities sold or matured	(9		)	(1		)
Losses related to securities intended or required to be sold	—			(6		)
Balance, end of period	$	107		$	124
Interest revenue related to debt securities is recognized in our consolidated statement of income using the interest method, or on a basis approximating a level rate of return over the contractual or estimated life of the security. The level rate of return considers any nonrefundable fees or costs, as well as purchase premiums or discounts, resulting in amortization or accretion, accordingly.
For debt securities acquired for which we consider it probable as of the date of acquisition that we will be unable to collect all contractually required principal, interest and other payments, the excess of our estimate of undiscounted future cash flows from these securities over their initial recorded investment is accreted into interest revenue on a level-yield basis over the securities’ estimated remaining terms. Subsequent decreases in these securities’ expected future cash flows are either recognized prospectively through an adjustment of the yields on the securities over their remaining terms, or are evaluated for other-than-temporary impairment. Increases in expected future cash flows are recognized prospectively over the securities’ estimated remaining terms through the recalculation of their yields.
For certain debt securities acquired which are considered to be beneficial interests in securitized financial assets, the excess of our estimate of undiscounted future cash flows from these securities over their initial recorded investment is accreted into interest revenue on a level-yield basis over the securities’ estimated remaining terms. Subsequent decreases in these securities’ expected future cash flows are either recognized prospectively through an adjustment of the yields on the securities over their remaining terms, or are evaluated for other-than-temporary impairment. Increases in expected future cash flows are recognized prospectively over the securities’ estimated remaining terms through the recalculation of their yields.
Impairment:
We conduct periodic reviews of individual securities to assess whether other-than-temporary impairment exists. For information about the review of securities for impairment, refer to pages 147 to 150 within note 3 of the 2014 Form 10-K.
In the aggregate, we recorded $1 million other-than-temporary impairment in three months ended March 31, 2015, compared to $9 million in the three months ended March 31, 2014, respectively, as summarized below:
Three months ended March 31, 2015:
•	$1 million (non-U.S. mortgage-backed securities) resulted from adverse changes in the timing of expected future cash flows from the securities.
Three months ended March 31, 2014:
•	$9 million was associated with expected credit losses.
After a review of the investment portfolio, taking into consideration current economic conditions, adverse situations that might affect our ability to fully collect principal and interest, the timing of future payments, the credit quality and performance of the collateral underlying mortgage- and asset-backed securities and other relevant factors, and excluding other-than-temporary impairment recorded in the three months ended March 31, 2015, management considers the aggregate decline in fair value of the investment securities portfolio and the resulting gross pre-tax unrealized losses of $442 million as of March 31, 2015, related to 1,189 securities, to be temporary, and not the result of any material changes in the credit characteristics of the securities.

Loans_and_Leases

Loans and Leases	3 Months Ended
	Mar. 31, 2015
Loans and Leases Receivable Disclosure [Abstract]
Loans and Leases	Loans and Leases
	We segregate our loans and leases into two segments: institutional and commercial real estate, or CRE. Within the institutional and CRE segments, we further segregate the receivables into classes based on their risk characteristics, their initial measurement attributes and the methods we use to monitor and assess credit risk. For additional information on our loans and leases, including our internal risk-rating system used to assess our risk of credit loss for each loan or lease, refer to note 4 on pages 150 to 154 of the 2014 Form 10-K.
	The following table presents our recorded investment in loans and leases, by segment and class, as of the dates indicated:
	(In millions)	March 31, 2015			December 31, 2014
	Institutional:
	Investment funds:
	U.S.	$	11,228		$	11,388
	Non-U.S.	2,232			2,333
	Commercial and financial:
	U.S.	3,294			3,061
	Non-U.S.	468			256
	Purchased receivables:
	U.S.	115			124
	Non-U.S.	4			6
	Lease financing:
	U.S.	334			335
	Non-U.S.	609			668
	Total institutional	18,284			18,171
	Commercial real estate:
	U.S.	35			28
	Total loans and leases	18,319			18,199
	Allowance for loan losses	(41		)	(38		)
	Loans and leases, net of allowance for loan losses	$	18,278		$	18,161
	Short-duration advances to our clients included in the institutional segment were $4.08 billion and $3.54 billion as of March 31, 2015 and December 31, 2014, respectively. These short-duration advances provide liquidity to fund clients in support of their transaction flows associated with securities settlement activities.
	The commercial-and-financial class in the institutional segment presented in the preceding table included approximately $2.53 billion and $2.07 billion of senior secured bank loans as of March 31, 2015 and December 31, 2014, respectively. These senior secured bank loans are included in the “speculative” category in the credit-quality-indicator tables presented below. As of March 31, 2015 and December 31, 2014, our allowance for loan losses included approximately $30 million and $26 million, respectively, related to these loans.
	The following tables present our recorded investment in each class of loans and leases by credit quality indicator as of the dates indicated:
		Institutional										Commercial Real Estate
	March 31, 2015	Investment			Commercial and Financial			Purchased		Lease		Property Development		Other		Total
		Funds						Receivables		Financing						Loans and
	(In millions)															Leases
	Investment grade(1)	$	13,351		$	1,132		$	119	$	916	$	—	$	28	$	15,546
	Speculative(2)	109			2,630			—		27		7		—		2,773
	Total	$	13,460		$	3,762		$	119	$	943	$	7	$	28	$	18,319
		Institutional										Commercial Real Estate
	December 31, 2014	Investment			Commercial and Financial			Purchased		Lease		Property Development		Other		Total
		Funds						Receivables		Financing						Loans and
	(In millions)															Leases
	Investment grade(1)	$	13,304		$	1,011		$	130	$	976	$	—	$	—	$	15,421
	Speculative(2)	417			2,306			—		27		—		28		2,778
	Total	$	13,721		$	3,317		$	130	$	1,003	$	—	$	28	$	18,199
	(1) Investment-grade loans and leases consist of counterparties with strong credit quality and low expected credit risk and probability of default. Ratings apply to counterparties with a strong capacity to support the timely repayment of any financial commitment.
	(2) Speculative loans and leases consist of counterparties that face ongoing uncertainties or exposure to business, financial, or economic downturns. However, these counterparties may have financial flexibility or access to financial alternatives, which allow for financial commitments to be met.
	The following table presents our recorded investment in loans and leases, disaggregated based on our impairment methodology, as of the dates indicated:
		March 31, 2015								December 31, 2014
	(In millions)	Institutional			Commercial Real Estate			Total Loans and Leases		Institutional		Commercial Real Estate		Total Loans and Leases
	Loans and leases:
	Collectively evaluated for impairment(1)	$	18,284		$	35		$	18,319	$	18,171	$	28	$	18,199
	Total	$	18,284		$	35		$	18,319	$	18,171	$	28	$	18,199
	(1) For those portfolios where there are a small number of loans each with a large balance, we review each loan annually for indicators of impairment. For those loans where no such indicators are identified, the loans are collectively evaluated for impairment. As of March 31, 2015 and December 31, 2014, all of the allowance for loan losses of $41 million and $38 million, respectively, related to institutional loans collectively evaluated for impairment.
	The following table presents information related to our recorded investment in impaired loans and leases as of the dates indicated:
		March 31, 2015						December 31, 2014
	(In millions)	Recorded Investment(1)			Unpaid			Recorded Investment(1)		Unpaid
					Principal					Principal
					Balance(2)					Balance(2)
	With no related allowance recorded:
	CRE—property development—acquired credit-impaired	$	—		$	34		$	—	$	34
	CRE—other—acquired credit-impaired	—			22			—		22
	Total CRE	$	—		$	56		$	—	$	56
	(1) As of March 31, 2015 and December 31, 2014, we have no recorded investment in institutional loans.
	(2) As of March 31, 2015 and December 31, 2014, all of the allowance for loan losses of $41 million and $38 million, respectively, related to institutional loans collectively evaluated for impairment.
	In certain circumstances, we restructure troubled loans by granting concessions to borrowers experiencing financial difficulty. Once restructured, the loans are generally considered impaired until their maturity, regardless of whether the borrowers perform under the modified terms of the loans. No loans were modified in troubled debt restructurings in the three months ended March 31, 2015 and the year ended December 31, 2014.
	As of March 31, 2015 and December 31, 2014, no institutional loans or leases and no CRE loans were on non-accrual status or 90 days or more contractually past due.
	The following table presents activity in the allowance for loan losses for the periods indicated:
		Three Months Ended March 31,
	2015			2014
(In millions)	Total Loans and Leases			Total Loans and Leases
Allowance for loan losses(1):
Beginning balance	$	37		$	28
Provisions	4			2
Ending balance	$	41		$	30
(1) As of March 31, 2015, approximately $30 million of our allowance for loan losses was related to senior secured bank loans included in the institutional segment; the remaining $11 million was related to other commercial-and-financial loans in the institutional segment.
The provision of $4 million recorded in the three months ended March 31, 2015 was associated with the secured bank loans as the portfolio continue to grow and become more seasoned. The senior secured bank loans are held in connection with our participation in loan syndications in the non-investment-grade lending market.
Loans and leases are reviewed on a regular basis, and any provisions for loan losses that are recorded reflect management's estimate of the amount necessary to maintain the allowance for loan losses at a level considered appropriate to absorb estimated incurred losses in the loan-and-lease portfolio.

Goodwill_and_Other_Intangible_

Goodwill and Other Intangible Assets	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets
	The following table presents changes in the carrying amount of goodwill during the periods indicated:
		Three Months Ended March 31,
		2015									2014
	(In millions)	Investment			Investment			Total			Investment			Investment			Total
		Servicing			Management						Servicing			Management
	Goodwill:
	Beginning balance	$	5,793		$	33		$	5,826		$	5,999		$	37		$	6,036
	Foreign currency translation and other, net	(160		)	(3		)	(163		)	2			—			2
	Ending balance	$	5,633		$	30		$	5,663		$	6,001		$	37		$	6,038
	The following table presents changes in the net carrying amount of other intangible assets during the periods indicated:
		Three Months Ended March 31,
		2015									2014
	(In millions)	Investment			Investment			Total			Investment			Investment			Total
		Servicing			Management						Servicing			Management
	Other intangible assets:
	Beginning balance	$	1,998		$	27		$	2,025		$	2,321		$	39		$	2,360
	Amortization	(48		)	(2		)	(50		)	(52		)	(2		)	(54		)
	Foreign currency translation and other, net	(81		)	(2		)	(83		)	—			—			—
	Ending balance	$	1,869		$	23		$	1,892		$	2,269		$	37		$	2,306
	The following table presents the gross carrying amount, accumulated amortization and net carrying amount of other intangible assets by type as of the dates indicated:
		March 31, 2015									December 31, 2014
	(In millions)	Gross			Accumulated			Net			Gross			Accumulated			Net
		Carrying			Amortization			Carrying			Carrying			Amortization			Carrying
		Amount						Amount			Amount						Amount
	Client relationships	$	2,471		$	(1,087	)	$	1,384		$	2,569		$	(1,088	)	$	1,481
	Core deposits	664			(220		)	444			688			(219		)	469
	Other	170			(106		)	64			214			(139		)	75
	Total	$	3,305		$	(1,413	)	$	1,892		$	3,471		$	(1,446	)	$	2,025

Other_Assets

Other Assets	3 Months Ended
	Mar. 31, 2015
Other Assets [Abstract]
Other Assets	Other Assets
	The following table presents the components of other assets as of the dates indicated:
	(In millions)	March 31, 2015		December 31, 2014
	Collateral deposits, net	$	22,094	$	18,134
	Unrealized gains on derivative financial instruments, net	8,048		7,934
	Bank-owned life insurance	2,419		2,402
	Investments in joint ventures and other unconsolidated entities	1,875		1,798
	Accounts receivable	1,087		513
	Receivable for securities settlement	419		218
	Prepaid expenses	376		259
	Income taxes receivable	295		396
	Deferred tax assets, net of valuation allowance	189		214
	Deposits with clearing organizations	181		197
	Receivable for securities sold	45		—
	Other(1)	521		535
	Total	$	37,549	$	32,600
	(1)	Includes other real estate owned of approximately $63 million and $62 million as of March 31, 2015 and December 31, 2014, respectively.

Commitments_and_Guarantees

Commitments and Guarantees	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Guarantees	Commitments and Guarantees
	For additional information regarding our commitments and guarantees, refer to note 10 on pages 159 to 160 of the 2014 Form 10-K.
	Commitments:
	We had unfunded off-balance sheet commitments to extend credit totaling $23.88 billion and $24.43 billion as of March 31, 2015 and December 31, 2014, respectively. The potential losses associated with these commitments equal the gross contractual amounts, and do not consider the value of any collateral. As of March 31, 2015, approximately 78% of our unfunded commitments to extend credit expire within one year. Since many of these commitments are expected to expire or renew without being drawn upon, the gross contractual amounts do not necessarily represent our future cash requirements.
	Guarantees:
	Off-balance sheet guarantees comprise indemnified securities financing, stable value protection, unfunded commitments to purchase assets, and standby letters of credit. The following table, which presents the aggregate gross contractual amounts of our off-balance sheet guarantees as of the dates indicated, does not consider the value of any collateral, which may mitigate any potential loss. Amounts presented do not reflect participations to independent third parties.
	(In millions)	March 31, 2015		December 31, 2014
	Indemnified securities financing	$	348,960	$	349,766
	Stable value protection	23,425		23,409
	Asset purchase agreements	4,212		4,107
	Standby letters of credit	4,782		4,720
	Indemnified Securities Financing
	On behalf of our clients, we lend their securities, as agent, to brokers and other institutions. In most circumstances, we indemnify our clients for the fair market value of those securities against a failure of the borrower to return such securities.
	The following table summarizes the aggregate fair values of indemnified securities financing and related collateral, as well as collateral invested in indemnified repurchase agreements, as of the dates indicated:
	(In millions)	March 31, 2015		December 31, 2014
	Fair value of indemnified securities financing	$	348,960	$	349,766
	Fair value of cash and securities held by us, as agent, as collateral for indemnified securities financing	364,212		364,411
	Fair value of collateral for indemnified securities financing invested in indemnified repurchase agreements	78,163		85,309
	Fair value of cash and securities held by us or our agents as collateral for investments in indemnified repurchase agreements	83,256		90,819
	In certain cases, we participate in securities finance transactions as a principal. As a principal, we borrow securities from the lending client and then lend such securities to the subsequent borrower, either a State Street client or a broker/dealer. Collateral provided and received in connection with such transactions is recorded in other assets and accrued expenses and other liabilities, respectively, in our consolidated statement of condition. As of March 31, 2015 and December 31, 2014, we had approximately $19.85 billion and $15.94 billion, respectively, of collateral provided and approximately $6.96 billion and $6.48 billion, respectively, of collateral received from clients in connection with our participation in principal securities finance transactions.
	Stable Value Protection
	In the normal course of our business, we offer products that provide book-value protection, primarily to plan participants in stable value funds managed by non-affiliated investment managers of post-retirement defined contribution benefit plans, particularly 401(k) plans. The book-value protection is provided on portfolios of intermediate investment grade fixed-income securities, and is intended to provide safety and stable growth of principal invested. The protection is intended to cover any shortfall in the event that a significant number of plan participants withdraw funds when book value exceeds market value and the liquidation of the assets is not sufficient to redeem the participants. The investment parameters of the underlying portfolios, combined with structural protections, are designed to provide cushion and guard against payments even under extreme stress scenarios.
	These contingencies are individually accounted for as derivative financial instruments. The notional amounts of the stable value contracts are presented as “derivatives not designated as hedging instruments” in the table of aggregate notional amounts of derivative financial instruments provided in note 12. We have not made a payment under these contingencies that we consider material to our consolidated financial condition, and management believes that the probability of payment under these contingencies in the future, that we would consider material to our consolidated financial condition, is remote.

Contingencies

Contingencies	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies
	Legal and Regulatory Matters:
	In the ordinary course of business, we and our subsidiaries are involved in disputes, litigation, and governmental or regulatory inquiries and investigations, both pending and threatened. These matters, if resolved adversely against us or settled, may result in monetary damages, fines and penalties or require changes in our business practices. The resolution or settlement of these matters is inherently difficult to predict. Based on our assessment of these pending matters, we do not believe that the amount of any judgment, settlement or other action arising from any pending matter is likely to have a material adverse effect on our consolidated financial condition.  However, an adverse outcome in certain of the matters described below could have a material adverse effect on our consolidated results of operations for the period in which such matter is resolved, or an accrual is determined to be required on our consolidated financial condition, or on our reputation.
	We evaluate our needs for accruals of loss contingencies related to legal proceedings on a case-by-case basis. When we have a liability that we deem probable and that we deem can be reasonably estimated as of the date of our consolidated financial statements, we accrue for our estimate of the loss. We also consider a loss probable and establish an accrual when we make, or intend to make, an offer of settlement. Once established, an accrual is subject to subsequent adjustment as a result of additional information. The resolution of proceedings and the reasonably estimable loss (or range thereof) are inherently difficult to predict, especially in the early stages of proceedings. Even if a loss is probable, due to many complex factors, such as speed of discovery and the timing of court decisions or rulings, a loss or range of loss might not be reasonably estimated until the later stages of the proceeding.
	As of March 31, 2015, our aggregate accruals for legal loss contingencies and regulatory matters totaled approximately $358 million. To the extent that we have established accruals in our consolidated statement of condition for probable loss contingencies, such accruals may not be sufficient to cover our ultimate financial exposure associated with any settlements or judgments. We may be subject to proceedings in the future that, if adversely resolved, would have a material adverse effect on our businesses or on our future consolidated financial statements. Except where otherwise noted below, we have not established accruals with respect to the claims discussed and do not believe that potential exposure is probable and can be reasonably estimated.
	The following discussion provides information with respect to significant legal and regulatory matters.
	Securities Finance
	Two related participants in our agency securities lending program have brought suit against us challenging actions taken by us in response to their withdrawal from the program. We believe that certain withdrawals by these participants were inconsistent with the redemption policy applicable to the agency lending collateral pools and, consequently, redeemed their remaining interests through an in-kind distribution that reflected the assets these participants would have received had they acted in accordance with the collateral pools' redemption policy. In taking these actions, we believe that we acted in the best interests of all participants in the collateral pools. The two participants have asserted damages of $125 million, an amount that plaintiffs attribute to alleged deficiencies in the methodology that State Street used to construct the in-kind distribution and alleged errors in the pricing of the securities that plaintiffs received on or about August 2009. While management does not believe that such difference is an appropriate measure of damages, we have been informed that the participants liquidated these securities in June 2013, and we estimate the loss on those sales to be approximately $11 million. Discovery with respect to this matter is expected to be completed in 2015. As of March 31, 2015, we had $10 million accrued in connection with this matter.
	Foreign Exchange
	We offer our custody clients and their investment managers the option to route foreign exchange transactions to our foreign exchange desk through our asset servicing operation. We record as revenue an amount approximately equal to the difference between the rates we set for those trades and indicative interbank market rates at the time of settlement of the trade.
	As discussed more fully below, claims have been asserted on behalf of certain current and former custody clients, and future claims may be asserted, alleging that our indirect foreign exchange rates (including the differences between those rates and indicative interbank market rates at the time we executed the trades) were not adequately disclosed or were otherwise improper, and seeking to recover, among other things, the full amount of the revenue we obtained from our indirect foreign exchange trading with them.
	In October 2009, the Attorney General of the State of California commenced an action under the California False Claims Act and California Business and Professional Code related to services State Street provides to California state pension plans. The California Attorney General asserts that the pricing of certain foreign exchange trades for these pension plans was governed by the custody contracts for these plans and that our pricing was not consistent with the terms of those contracts and related disclosures to the plans, and that, as a result, State Street made false claims and engaged in unfair competition. The Attorney General asserts actual damages of approximately $100 million for periods from 2001 to 2009 and seeks additional penalties, including treble damages. This action is in the discovery phase.
	We provide custody services to and engage in principal foreign exchange trading with government pension plans in other jurisdictions. Since the commencement of the litigation in California, attorneys general and other government authorities from a number of jurisdictions, as well as U.S. Attorney's offices, the U.S. Department of Labor and the SEC, have requested information or issued subpoenas in connection with inquiries into the pricing of our indirect foreign exchange trading. We continue to respond to such inquiries and subpoenas.
	We engage in indirect foreign exchange trading with a broad range of custody clients in the U.S. and internationally. We have responded and are responding to information requests from a number of clients concerning our indirect foreign exchange rates. In February 2011, a putative class action was filed in federal court in Boston seeking unspecified damages, including treble damages, on behalf of all custodial clients that executed certain foreign exchange transactions with State Street from 1998 to 2009. The putative class action alleges, among other things, that the rates at which State Street executed foreign currency trades constituted an unfair and deceptive practice under Massachusetts law and a breach of the duty of loyalty.
	Two other putative class actions are currently pending in federal court in Boston alleging various violations of ERISA on behalf of all ERISA plans custodied with us that executed indirect foreign exchange trades with State Street from 1998 onward. The complaints allege that State Street caused class members to pay unfair and unreasonable rates on indirect foreign exchange trades with State Street. The complaints seek unspecified damages, disgorgement of profits, and other equitable relief. Other claims may be asserted in the future, including in response to developments in the actions discussed above or governmental proceedings.
	We expect that plaintiffs will seek to recover their share of all or a portion of the revenue that we have recorded from indirect foreign exchange trades. We cannot predict whether a court, in the event of an adverse resolution, would consider our revenue to be the appropriate measure of damages.
	The following table summarizes our estimated total revenue worldwide from indirect foreign exchange trading for the periods indicated:
	(In millions)	Revenue from indirect foreign exchange trading
	Twelve Months Ended December 31, 2008	$	462
	Twelve Months Ended December 31, 2009	369
	Twelve Months Ended December 31, 2010	336
	Twelve Months Ended December 31, 2011	331
	Twelve Months Ended December 31, 2012	248
	Twelve Months Ended December 31, 2013	285
	Twelve Months Ended December 31, 2014	246
	Three Months Ended March 31, 2015	68
	We believe that the amount of our revenue from such trading has been of a similar or lesser order of magnitude for many years prior to 2008. Our revenue calculations related to indirect foreign exchange trading reflect a judgment concerning the relationship between the rates we charge for indirect foreign exchange execution and indicative interbank market rates near in time to execution. Our revenue from foreign exchange trading generally depends on the difference between the rates we set for those indirect trades and indicative interbank market rates at the time of settlement of the trade.
	As of March 31, 2015, we have accrued a total of $335 million associated with indirect foreign exchange client activities, including $150 million recorded in the first quarter of 2015. This accrual reflects the current status of continued negotiations in connection with our intention to seek to resolve the outstanding claims asserted in the United States against us by federal governmental entities and civil litigants with regard to our indirect foreign exchange client activities. In the course of our negotiations seeking to resolve the outstanding asserted claims, we have received demands for settlement that aggregate up to $925 million. There can be no assurance that we will reach settlements in these matters, and the cost of any settlements or other resolutions of these matters could materially exceed our accrual and the amounts currently demanded of us for settlement. Our current efforts, even if successful, may not address all of our potential legal exposure arising out of our indirect foreign exchange client activities, and other claims, which may be material, could be asserted against us. An adverse outcome with respect to one or more claims relating to our indirect foreign exchange client activities could have a material adverse effect on our reputation, on our consolidated results of operations for the period in which the adverse outcome occurs (or an accrual is determined to be required), or on our consolidated financial condition.
	Transition Management
	In January 2014, we entered into a settlement with the U.K. Financial Conduct Authority, or FCA, pursuant to which we paid a fine of £22.9 million (approximately $37.8 million), as a result of our having charged six clients of our U.K. transition management business during 2010 and 2011 amounts in excess of the contractual terms. The SEC and the U.S. Attorney are conducting separate investigations into this matter. As of March 31, 2015, we had remaining accruals of approximately $2.7 million for indemnification costs associated with this matter.
	Investment Servicing
	State Street has been named as a defendant in related complaints by investment management clients of TAG Virgin Islands, Inc., or TAG, who hold or held custodial accounts with State Street. The complaints collectively have alleged various claims in connection with certain assets managed by TAG. As of March 31, 2015, one action remains pending. As of March 31, 2015, we had $4.3 million accrued with respect to these matters.
	Income Taxes:
	In determining our provision for income taxes, we make certain judgments and interpretations with respect to tax laws in jurisdictions in which we have business operations. Because of the complex nature of these laws, in the normal course of our business, we are subject to challenges from U.S. and non-U.S. income tax authorities regarding the amount of income taxes due. These challenges may result in adjustments to the timing or amount of taxable income or deductions or the allocation of taxable income among tax jurisdictions. We recognize a tax benefit when it is more likely than not that our position will result in a tax deduction or credit. Unrecognized tax benefits totaled approximately $163 million as of both March 31, 2015 and December 31, 2014.
	We are presently under audit by a number of tax authorities. The earliest tax year open to examination in jurisdictions where we have material operations is 2009. The Internal Revenue Service, or IRS, completed their audit field procedures for the current audit related to our U.S. income tax returns for the tax years 2010 and 2011.

Variable_Interest_Entities

Variable Interest Entities	3 Months Ended
	Mar. 31, 2015
Variable Interest Entities [Abstract]
Variable Interest Entities	Variable Interest Entities
	For additional information on our variable interest entities, or VIEs, refer to note 12 on pages 162 to 164 of the 2014 Form 10-K.
	Tax-Exempt Investment Program:
	In the normal course of our business, we structure and sell certificated interests in pools of tax-exempt investment-grade assets, principally to our mutual fund clients. We structure these pools as partnership trusts, and the assets and liabilities of the trusts are recorded in our consolidated statement of condition as investment securities available for sale and other short-term borrowings. As of March 31, 2015 and December 31, 2014, we carried investment securities available for sale, composed of securities related to state and political subdivisions, with a fair value of $2.24 billion and $2.27 billion, respectively, and other short-term borrowings of $1.84 billion and $1.87 billion, respectively, in our consolidated statement of condition in connection with these trusts. The interest revenue and interest expense generated by the investments and certificated interests, respectively, are recorded as components of net interest revenue when earned or incurred.
	The trusts had a weighted-average life of approximately 5.7 years as of March 31, 2015, compared to approximately 5.9 years as of December 31, 2014.
	Under separate legal agreements, we provide standby bond-purchase agreements to these trusts and, with respect to certain securities, letters of credit. Our commitments to the trusts under these standby bond-purchase agreements and letters of credit totaled $1.88 billion and $669 million, respectively, as of March 31, 2015, none of which was utilized as of that date.
	Interests in Sponsored Investment Funds:
	As of March 31, 2015, the aggregate assets and liabilities of our consolidated sponsored investment fund totaled $68 million and $14 million, respectively. As of December 31, 2014, the aggregate assets and liabilities of our consolidated sponsored investment fund totaled $65 million and $13 million, respectively.
	As of March 31, 2015 our potential maximum total exposure associated with the consolidated sponsored investment fund totaled $54 million and represented the value of our economic ownership interest in the fund.
	As of March 31, 2015 and December 31, 2014, we managed certain sponsored investment funds, considered VIEs, in which we held a variable interest but for which we were not deemed to be the primary beneficiary. Our potential maximum loss exposure related to these unconsolidated funds totaled $88 million and $45 million as of March 31, 2015 and December 31, 2014, respectively, and represented the carrying value of our seed capital investment, which is recorded in either investment securities available for sale or other assets in our consolidated statement of condition. The amount of loss we may recognize during any period is limited to the carrying amount of our seed capital investment in the unconsolidated fund.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Income	3 Months Ended
	Mar. 31, 2015
Stockholders' Equity Note [Abstract]
Accumulated Other Comprehensive Income	Preferred Stock:
	Preferred Stock, Series E
	In the three months ended March 31, 2015, we declared dividends on our Series E preferred stock of $1,833 per share, or approximately $0.46 per depositary share, totaling approximately $14 million. We did not declare a dividend on the Series E preferred stock in the three months ended March 31, 2014.
	Preferred Stock, Series D
	In the three months ended March 31, 2015, we declared aggregate dividends on our Series D preferred stock of $1,475 per share, or approximately $0.37 per depositary share, totaling approximately $11 million. We did not declare a dividend on the Series D preferred stock in the three months ended March 31, 2014.
	Preferred Stock, Series C
	In the three months ended March 31, 2015, we declared aggregate dividends on our Series C preferred stock of $1,313 per share, or approximately $0.33 per depositary share, totaling approximately $6 million. In the three months ended March 31, 2014, we declared aggregate dividends on our Series C preferred stock of $1,313 per share, or approximately $0.33 per depositary share, totaling approximately $6 million.
	Common Stock:
	In March 2015 our Board of Directors, or Board, approved a common stock purchase program authorizing the purchase of up to $1.8 billion of our common stock through June 30, 2016. No shares were purchased by us under this program in the three months ended March 31, 2015.
	In the three months ended March 31, 2015, we purchased approximately 6.3 million shares of our common stock at an average per-share cost of $74.88 and an aggregate cost of approximately $470 million under a previous program approved by the Board in March 2014. As of March 31, 2015, no shares remained available for purchases of our common stock under the program. Shares acquired under the program which remained unissued as of March 31, 2015 were recorded as treasury stock in our consolidated statement of condition as of March 31, 2015.
	In the three months ended March 31, 2015, we declared aggregate common stock dividends of $0.30 per share, totaling approximately $124 million, compared to aggregate common stock dividends of $0.26 per share, totaling approximately $112 million, declared in the three months ended March 31, 2014.
	Accumulated Other Comprehensive Income (Loss):
	The following table presents the after-tax components of AOCI as of the dates indicated:
	(In millions)	March 31, 2015			December 31, 2014
	Net unrealized gains on cash flow hedges	$	288		$	276
	Net unrealized gains (losses) on available-for-sale securities portfolio	472			273
	Net unrealized gains (losses) related to reclassified available-for-sale securities	35			39
	Net unrealized gains (losses) on available-for-sale securities	507			312
	Net unrealized losses on available-for-sale securities designated in fair value hedges	(136		)	(121		)
	Other-than-temporary impairment on available-for-sale securities related to factors other than credit	—			1
	Net unrealized losses on hedges of net investments in non-U.S. subsidiaries	(14		)	(14		)
	Other-than-temporary impairment on held-to-maturity securities related to factors other than credit	(25		)	(29		)
	Net unrealized losses on retirement plans	(267		)	(272		)
	Foreign currency translation	(1,359		)	(660		)
	Total	$	(1,006	)	$	(507	)
	The following tables present changes in AOCI by component, net of related taxes, for the periods indicated:
		Three Months Ended March 31, 2015
	(In millions)	Net Unrealized Gains (Losses) on Cash Flow Hedges			Net Unrealized Gains (Losses) on Available-for-Sale Securities			Net Unrealized Losses on Hedges of Net Investments in Non-U.S. Subsidiaries			Other-Than-Temporary Impairment on Held-to-Maturity Securities			Net Unrealized Losses on Retirement Plans			Foreign Currency Translation			Total
	Balance as of December 31, 2014	$	276		$	192		$	(14	)	$	(29	)	$	(272	)	$	(660	)	$	(507	)
	Other comprehensive income (loss) before reclassifications	11			179			—			5			—			(699		)	(504		)
	Amounts reclassified into earnings	1			—			—			(1		)	5			—			5
	Other comprehensive income (loss)	12			179			—			4			5			(699		)	(499		)
	Balance as of March 31, 2015	$	288		$	371		$	(14	)	$	(25	)	$	(267	)	$	(1,359	)	$	(1,006	)
		Three Months Ended March 31, 2014
	(In millions)	Net Unrealized Gains (Losses) on Cash Flow Hedges			Net Unrealized Gains (Losses) on Available-for-Sale Securities			Net Unrealized Losses on Hedges of Net Investments in Non-U.S. Subsidiaries			Other-Than-Temporary Impairment on Held-to-Maturity Securities			Net Unrealized Losses on Retirement Plans			Foreign Currency Translation			Total
	Balance as of December 31, 2013	$	161		$	(221	)	$	(14	)	$	(47	)	$	(203	)	$	229		$	(95	)
	Other comprehensive income (loss) before reclassifications	(8		)	258			—			8			1			27			286
	Amounts reclassified into earnings	1			(9		)	—			—			5			—			(3		)
	Other comprehensive income (loss)	(7		)	249			—			8			6			27			283
	Balance as of March 31, 2014	$	154		$	28		$	(14	)	$	(39	)	$	(197	)	$	256		$	188
	The following table presents after-tax reclassifications into earnings for the periods indicated:
		Three Months Ended March 31,
		2015			2014
	(In millions)	Amounts Reclassified into Earnings						Affected Line Item in Consolidated Statement of Income
	Cash flow hedges:
	Interest-rate contracts	$	1		$	1		Net interest revenue
	Available-for-sale securities:
	Net realized gains from sales of available-for-sale securities, net of related taxes of ($6)	—			(9		)	Net gains (losses) from sales of available-for-sale securities
	Held-to-maturity securities:
	Other-than-temporary impairment on held-to-maturity securities related to factors other than credit	(1		)	—			Losses reclassified (from) to other comprehensive income
	Retirement plans:
	Amortization of actuarial losses, net of related taxes of ($4) and tax benefits of $3, respectively	5			5			Compensation and employee benefits expenses
	Total reclassifications out of AOCI	$	5		$	(3	)

Regulatory_Capital

Regulatory Capital	3 Months Ended
	Mar. 31, 2015
Banking and Thrift [Abstract]
Regulatory Capital	Regulatory Capital
	We are subject to various regulatory capital requirements administered by federal banking agencies. Failure to meet minimum regulatory capital requirements can initiate certain mandatory and discretionary actions by regulators that, if undertaken, could have a direct material effect on our consolidated financial condition. Under current regulatory capital adequacy guidelines, we must meet specified capital requirements that involve quantitative measures of our consolidated assets, liabilities and off-balance sheet exposures calculated in conformity with regulatory accounting practices. Our capital components and their classifications are subject to qualitative judgments by regulators about components, risk weightings and other factors. For additional information on regulatory capital, and the requirements to which we are subject, refer to note 15, Regulatory Capital on pages 170 to 173 in the 2014 Form 10-K.
	As required by the Dodd-Frank Wall Street Reform and Consumer Protection Act, or Dodd-Frank Act, enacted in 2010, State Street and State Street Bank, as advanced approaches banking organizations, are subject to a permanent "capital floor" in the calculation and assessment of their regulatory capital adequacy by U.S. banking regulators. Beginning on January 1, 2015, we are required to calculate our risk-based capital ratios using both the advanced approaches and the standardized approach. As a result, from January 1, 2015 going forward, our risk-based capital ratios for regulatory assessment purposes will be the lower of each ratio calculated under the standardized approach and the advanced approaches.
	The methods for the calculation of our and State Street Bank's risk-based capital ratios will change as the provisions of the Basel III final rule related to the numerator (capital) and denominator (risk-weighted assets) are phased in, and as we begin calculating our risk-weighted assets using the advanced approaches. These ongoing methodological changes will result in differences in our reported capital ratios from one reporting period to the next that are independent of applicable changes to our capital base, our asset composition, our off-balance sheet exposures or our risk profile.
	As of March 31, 2015, State Street and State Street Bank exceeded all regulatory capital adequacy requirements to which they were subject. As of March 31, 2015, State Street Bank was categorized as “well capitalized” under the applicable regulatory capital adequacy framework, and exceeded all “well capitalized” ratio guidelines to which it was subject. Management believes that no conditions or events have occurred since March 31, 2015 that have changed the capital categorization of State Street Bank.
	The following table presents the regulatory capital structure, total risk-weighted assets, related regulatory capital ratios and the minimum required regulatory capital ratios for State Street and State Street Bank as of the dates indicated. As a result of changes in the methodologies used to calculate our regulatory capital ratios from period to period as the provisions of the Basel III final rule are phased in, the ratios presented in the table for each period-end are not directly comparable. Refer to the footnotes following the table.
						State Street												State Street Bank
	(Dollars in millions)					Basel III Advanced Approaches March 31, 2015(1)			Basel III Standardized Approach March 31, 2015(2)			Basel III Advanced Approaches December 31, 2014(1)			Basel III Transitional Approach December 31, 2014(3)			Basel III Advanced Approaches March 31, 2015(1)			Basel III Standardized Approach March 31, 2015(2)			Basel III Advanced Approaches December 31, 2014(1)			Basel III Transitional Approach December 31, 2014(3)
	Common shareholders' equity:
	Common stock and related surplus					$	10,248		$	10,248		$	10,295		$	10,295		$	10,901		$	10,901		$	10,867		$	10,867
	Retained earnings					15,135			15,135			14,882			14,882			9,801			9,801			9,416			9,416
	Accumulated other comprehensive income (loss)					(1,226		)	(1,226		)	(641		)	(641		)	(1,048		)	(1,048		)	(535		)	(535		)
	Treasury stock, at cost					(5,519		)	(5,519		)	(5,158		)	(5,158		)	—			—			—			—
	Total					18,638			18,638			19,378			19,378			19,654			19,654			19,748			19,748
	Regulatory capital adjustments:
	Goodwill and other intangible assets, net of associated deferred tax liabilities(4)					(5,932		)	(5,932		)	(5,869		)	(5,869		)	(5,632		)	(5,632		)	(5,577		)	(5,577		)
	Other adjustments					(62		)	(62		)	(36		)	(36		)	(102		)	(102		)	(128		)	(128		)
	Common equity tier 1 capital					12,644			12,644			13,473			13,473			13,920			13,920			14,043			14,043
	Preferred stock					1,961			1,961			1,961			1,961			—			—			—			—
	Trust preferred capital securities subject to phase-out from tier 1 capital					237			237			475			475			—			—			—			—
	Other adjustments					(94		)	(94		)	(145		)	(145		)	—			—			—			—
	Tier 1 capital					14,748			14,748			15,764			15,764			13,920			13,920			14,043			14,043
	Qualifying subordinated long-term debt					1,439			1,439			1,618			1,618			1,453			1,453			1,634			1,634
	Trust preferred capital securities phased out of tier 1 capital					713			713			475			475			—			—			—			—
	Other adjustments					2			2			4			4			—			—			—			—
	Total capital					$	16,902		$	16,902		$	17,861		$	17,861		$	15,373		$	15,373		$	15,677		$	15,677
	Risk-weighted assets:
	Credit risk					$	63,820		$	119,582		$	66,874		$	87,502		$	56,527		$	112,454		$	59,836		$	84,433
	Operational risk					35,765			NA			35,866			NA			35,348			NA			35,449			NA
	Market risk(5)					4,413			2,364			5,087			2,910			4,407			2,363			5,048			2,909
	Total risk-weighted assets					$	103,998		$	121,946		$	107,827		$	90,412		$	96,282		$	114,817		$	100,333		$	87,342
	Adjusted quarterly average assets					$	252,406		$	252,406		$	247,740		$	247,740		$	248,022		$	248,022		$	243,549		$	243,549
	Capital Ratios:	Minimum Requirements(6) 2015		Minimum Requirements(7) 2014
	Common equity tier 1 capital	4.5	%	4	%	12.2		%	10.4		%	12.5		%	14.9		%	14.5		%	12.1		%	14		%	16.1		%
	Tier 1 capital	6		5.5		14.2			12.1			14.6			17.4			14.5			12.1			14			16.1
	Total capital	8		8		16.3			13.9			16.6			19.8			16			13.4			15.6			17.9
	Tier 1 leverage	4		4		5.8			5.8			6.4			6.4			5.6			5.6			5.8			5.8
	NA: Not applicable.
	(1) Common equity tier 1 capital, tier 1 capital and total capital ratios as of March 31, 2015 and December 31, 2014 were calculated in conformity with the advanced approaches provisions of the Basel III final rule. Tier 1 leverage ratio as of March 31, 2015 and December 31, 2014 were calculated in conformity with the Basel III final rule.
	(2) Common equity tier 1 capital, tier 1 capital and total capital ratios as of March 31, 2015 were calculated in conformity with the standardized approach provisions of the Basel III final rule. Tier 1 leverage ratio as of March 31, 2015 was calculated in conformity with the Basel III final rule.
	(3) Common equity tier 1 capital, tier 1 capital, total capital and tier 1 leverage ratios as of December 31, 2014 were calculated in conformity with the transitional provisions of the Basel III final rule. Specifically, these ratios reflect common equity tier 1, tier 1 and total capital (the numerator) calculated in conformity with the provisions of the Basel III final rule, and total risk-weighted assets or, with respect to the tier 1 leverage ratio, quarterly average assets (in both cases, the denominator), calculated in conformity with the provisions of Basel I.
	(4) Amounts for State Street and State Street Bank as of March 31, 2015 consisted of goodwill, net of associated deferred tax liabilities, and 40% of other intangible assets, net of associated deferred tax liabilities. Amounts for State Street and State Street Bank as of December 31, 2014 consisted of goodwill, net of deferred tax liabilities and 20% of other intangible assets, net of associated deferred tax liabilities. Intangible assets, net of associated deferred tax liabilities is phased in as a deduction from capital, in conformity with the Basel III final rule.
	(5) Market risk risk-weighted assets reported in conformity with the Basel III advanced approaches included a credit valuation adjustment, or CVA, which reflected the risk of potential fair-value adjustments for credit risk reflected in our valuation of over-the-counter derivative contracts.  The CVA was not provided for in the final market risk capital rule; however, it was required by the advanced approaches provisions of the Basel III final rule.  State Street used the simple CVA approach in conformity with the Basel III advanced approaches.
	(6) Minimum requirements will be phased in up to full implementation beginning on January 1, 2019; minimum requirements listed are as of March 31, 2015.
	(7) Minimum requirements will be phased in up to full implementation beginning on January 1, 2019; minimum requirements listed are as of December 31, 2014.

Derivative_Financial_Instrumen

Derivative Financial Instruments	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments
	We use derivative financial instruments to support our clients' needs and to manage our interest-rate and currency risk. In undertaking these activities, we assume positions in both the foreign exchange and interest-rate markets by buying and selling cash instruments and using derivative financial instruments, including foreign exchange forward contracts, foreign exchange and interest-rate options and interest-rate swaps, interest-rate forward contracts and interest-rate futures. For information on our derivative instruments, including the related accounting policies, refer to note 16 on pages 173 to 179 in the 2014 10-K.
	Derivative financial instruments are also subject to credit and counterparty risk, which we manage by performing credit reviews, maintaining individual counterparty limits, entering into netting arrangements and requiring the receipt of collateral. Cash collateral received from and provided to counterparties in connection with derivative financial instruments is recorded in accrued expenses and other liabilities and other assets, respectively, in our consolidated statement of condition. As of March 31, 2015 and December 31, 2014, we had recorded approximately $1.49 billion and $1.79 billion, respectively, of cash collateral received from counterparties and approximately $4.87 billion and $4.79 billion, respectively, of cash collateral provided to counterparties in connection with derivative financial instruments in our consolidated statement of condition.
	Certain of our derivative assets and liabilities as of March 31, 2015 and December 31, 2014 are subject to master netting agreements with our derivative counterparties. Certain of these agreements contain credit risk-related contingent features in which the counterparty has the right to declare us in default and accelerate cash settlement of our net derivative liabilities with the counterparty in the event that our credit rating falls below specified levels. The aggregate fair value of all derivative instruments with credit risk-related contingent features that were in a net liability position as of March 31, 2015 totaled approximately $2.16 billion, against which we had no underlying collateral, due to timing differences with respect to the market-to market valuation of the collateral. If our credit rating were downgraded below levels specified in the agreements, the maximum additional amount of payments related to termination events that could have been required pursuant to these contingent features as of March 31, 2015 was approximately $2.16 billion. Such accelerated settlement would not affect our consolidated results of operations.
	Derivatives Not Designated as Hedging Instruments:
	In connection with our trading activities, we use derivative financial instruments in our role as a financial intermediary and as both a manager and servicer of financial assets, in order to accommodate our clients' investment and risk management needs. In addition, we use derivative financial instruments for risk management purposes as economic hedges, which are not formally designated as accounting hedges, in order to contribute to our overall corporate earnings and liquidity. These activities are designed to generate trading services revenue and to manage volatility in our net interest revenue. The level of market risk that we assume is a function of our overall objectives and liquidity needs, our clients' requirements and market volatility. Refer to pages 174 to 175 within note 16 in the 2014 Form 10-K for information on derivatives not designated as hedging instruments.
	Derivatives Designated as Hedging Instruments:
	In connection with our asset-and-liability management activities, we use derivative financial instruments to manage our interest-rate risk. Interest-rate risk, defined as the sensitivity of income or financial condition to variations in interest rates, is a significant non-trading market risk to which our assets and liabilities are exposed. We manage our interest-rate risk by identifying, quantifying and hedging our exposures, using fixed-rate portfolio securities and a variety of derivative financial instruments, most frequently interest-rate swaps and options (for example, interest-rate caps and floors). Interest-rate swap agreements alter the interest-rate characteristics of specific balance sheet assets or liabilities. When appropriate, forward-rate agreements, options on swaps, and exchange-traded futures and options are also used. Our hedging relationships are formally designated, and qualify for hedge accounting, as fair value or cash flow hedges. Refer to pages 175 to 179 within note 16 in the 2014 Form 10-K for information on derivatives designated as hedging instruments.
	Fair value hedges
	We have entered into interest-rate swap agreements to modify our interest revenue from certain available-for-sale investment securities from a fixed rate to a floating rate. The hedged trusts had a weighted-average life of approximately 5.7 years as of March 31, 2015, compared to 5.9 years as of December 31, 2014.
	We have entered into interest-rate swap agreements to modify our interest expense on three senior notes and one subordinated note from fixed rates to floating rates. The senior notes mature in 2018, 2023 and 2024 and pay fixed interest at annual rates of 1.35%, 3.70% and 3.30%, respectively. The subordinated note matures in 2023 and pays fixed interest at a 3.10% annual rate. The senior and subordinated notes are hedged with interest-rate swap contracts with notional amounts, maturities and fixed-rate coupon terms that align with the hedged notes.
	We have entered into forward foreign exchange contracts to hedge the change in fair value attributable to foreign exchange movements in the funding of non-functional currency-denominated investment securities. These forward contracts convert the foreign currency risk to U.S. dollars, thereby mitigating our exposure to fluctuations in the fair value of the securities attributable to changes in foreign exchange rates.
	Cash flow hedges
	We have entered into foreign exchange contracts to hedge the change in cash flows attributable to foreign exchange movements in the funding of non-functional currency-denominated investment securities. These foreign exchange contracts convert the foreign currency risk to U.S. dollars, thereby mitigating our exposure to fluctuations in the cash flows of the securities attributable to changes in foreign exchange rates.
	The following table presents the aggregate contractual, or notional, amounts of derivative financial instruments entered into in connection with our trading and asset-and-liability management activities as of the dates indicated:
	(In millions)	March 31,				December 31,
		2015				2014
	Derivatives not designated as hedging instruments:
	Interest-rate contracts:
	Swap agreements and forwards	$	474			$	645
	Options and caps purchased	4				7
	Options and caps written	4				7
	Futures	2,969				3,939
	Foreign exchange contracts:
	Forward, swap and spot	1,414,506				1,231,344
	Options purchased	3,008				2,767
	Options written	2,905				2,404
	Futures	21				—
	Credit derivative contracts:
	Credit swap agreements	226				191
	Commodity and equity contracts:
	Commodity(1)	61				26
	Equity(1)	92				2
	Other:
	Stable value contracts	23,425				23,409
	Deferred value awards(2)	417				210
	Derivatives designated as hedging instruments:
	Interest-rate contracts:
	Swap agreements	6,065				6,077
	Foreign exchange contracts:
	Forward and swap	2,605				2,705
	(1) Primarily composed of positions held by a consolidated sponsored investment fund, more fully described in note 9.
	(2) Represents grants of deferred value awards to employees; refer to discussion in this note under "Derivatives Not Designated as Hedging Instruments."
	In connection with our asset-and-liability management activities, we have entered into interest-rate contracts designated as fair value and cash flow hedges to manage our interest-rate risk. The following table presents the aggregate notional amounts of these interest-rate contracts and the related assets or liabilities being hedged as of the dates indicated:
		March 31, 2015(1)
	(In millions)	Fair
		Value
		Hedges
	Investment securities available for sale	$	2,565
	Long-term debt(2)	3,500
	Total	$	6,065
		December 31, 2014
	(In millions)	Fair
		Value
		Hedges
	Investment securities available for sale	$	2,577
	Long-term debt(2)	3,500
	Total	$	6,077
	(1) As of March 31, 2015 there were no interest-rate contracts designated as cash flow hedges.
	(2) As of March 31, 2015, these fair value hedges increased the carrying value of long-term debt presented in our consolidated statement of condition by $135 million. As of December 31, 2014, these fair value hedges decreased the carrying value of long-term debt presented in our consolidated statement of condition by $76 million.
	The following tables present the contractual and weighted-average interest rates for long-term debt, which include the effects of the fair value hedges presented in the table above, for the periods indicated:
		Three Months Ended March 31,
		2015						2014
		Contractual			Rate			Contractual			Rate
Rates		Including			Rates			Including
		Impact of Hedges						Impact of Hedges
Long-term debt	3.53	%		2.54	%		3.39	%		2.6	%
The following tables present the fair value of derivative financial instruments, excluding the impact of master netting agreements, recorded in our consolidated statement of condition as of the dates indicated. The impact of master netting agreements is disclosed in note 2.
Derivative Assets(1)
	Fair Value
(In millions)	March 31, 2015				December 31, 2014
Derivatives not designated as hedging instruments:
Foreign exchange contracts	$	15,610			$	14,626
Interest-rate contracts	12				15
Other derivative contracts	3				2
Total	$	15,625			$	14,643
Derivatives designated as hedging instruments:
Foreign exchange contracts	$	506			$	509
Interest-rate contracts	129				62
Total	$	635			$	571
(1) Derivative assets are included within other assets in our consolidated statement of condition.
Derivative Liabilities(1)
	Fair Value
(In millions)	March 31, 2015				December 31, 2014
Derivatives not designated as hedging instruments:
Foreign exchange contracts	$	17,053			$	14,922
Other derivative contracts	112				70
Interest-rate contracts	12				16
Total	$	17,177			$	15,008
Derivatives designated as hedging instruments:
Interest-rate contracts	$	220			$	223
Foreign exchange contracts	—				3
Total	$	220			$	226
(1) Derivative liabilities are included within other liabilities in our consolidated statement of condition.
The following tables present the impact of our use of derivative financial instruments on our consolidated statement of income for the periods indicated:
	Location of Gain (Loss) on		Amount of Gain (Loss) on Derivative Recognized
	Derivative in Consolidated		in Consolidated Statement of Income
	Statement of Income
			Three Months Ended March 31,
(In millions)			2015				2014
Derivatives not designated as hedging instruments:
Foreign exchange contracts	Trading services revenue		$	204			$	134
Interest-rate contracts	Processing fees and other revenue		1				—
Other derivative contracts	Trading services revenue		2				(1		)
Total			$	207			$	133
	Location of (Gain) Loss on		Amount of (Gain) Loss on Derivative Recognized
	Derivative in Consolidated		in Consolidated Statement of Income
	Statement of Income
			Three Months Ended March 31,
(In millions)			2015				2014
Derivatives not designated as hedging instruments:
Other derivative contracts	Compensation and employee benefits		$	59			$	49
Total			$	59			$	49
	Location of Gain (Loss) on Derivative in Consolidated Statement of Income		Amount of Gain								Hedged Item in Fair Value Hedging Relationship		Location of Gain (Loss) on Hedged Item in Consolidated Statement of Income	Amount of Gain
			(Loss) on Derivative											(Loss) on Hedged
			Recognized in											Item Recognized in
			Consolidated											Consolidated
			Statement of Income											Statement of Income
			Three Months Ended March 31,											Three Months Ended March 31,
(In millions)			2015				2014							2015			2014
Derivatives designated as fair value hedges:
Foreign exchange contracts	Processing fees and		$	(67	)		42				Investment securities		Processing fees and	$	67		$	(42	)
	other revenue												other revenue
Interest-rate contracts	Processing fees and		(25		)		(12		)		Available-for-sale securities		Processing fees and	25			12
	other revenue												other revenue(1)
Interest-rate contracts	Processing fees and		68				49				Long-term debt		Processing fees and	(65		)	(45		)
	other revenue												other revenue
Total			$	(24	)		$	79						$	27		$	(75	)
(1) Represents amounts reclassified out of or into other comprehensive income, or OCI. For the three months ended March 31, 2015, $15 million of unrealized losses on available-for-sale securities designated in fair value hedges were recognized in OCI. For the three months ended March 31, 2014, $10 million of unrealized gains on available-for-sale securities designated in fair value hedges were recognized in OCI.
Differences between the gains (losses) on the derivative and the gains (losses) on the hedged item, excluding any amounts recorded in net interest revenue, represent hedge ineffectiveness.
	Amount of Gain								Location of Gain (Loss) Reclassified from OCI to Consolidated Statement of Income		Amount of Gain						Location of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income		Amount of Gain
	(Loss) on Derivative										(Loss) Reclassified								(Loss) on Derivative
	Recognized in Other										from OCI to								Recognized in
	Comprehensive										Consolidated								Consolidated
	Income										Statement of Income								Statement of Income
	Three Months Ended March 31,										Three Months Ended March 31,								Three Months Ended March 31,
	2015				2014						2015			2014					2015		2014
(In millions)
Derivatives designated as cash flow hedges:
Interest-rate contracts	$	—			$	(1	)		Net interest revenue		$	(1	)	$	(1	)	Net interest revenue		$	—	$	1
Foreign exchange contracts	20				(12		)		Net interest revenue		—			—			Net interest revenue		2		1
Total	$	20			$	(13	)				$	(1	)	$	(1	)			$	2	$	2

Offsetting_Arrangements

Offsetting Arrangements	3 Months Ended
	Mar. 31, 2015
Offsetting [Abstract]
Offsetting Arrangements	Offsetting Arrangements
	We manage credit and counterparty risk by entering into enforceable netting agreements and other collateral arrangements with counterparties to derivative contracts and secured financing transactions, including resale and repurchase agreements, and principal securities borrowing and lending agreements. These netting agreements mitigate our counterparty credit risk by providing for a single net settlement with a counterparty of all financial transactions covered by the agreement in an event of default as defined under such agreement. In limited cases, a netting agreement may also provide for the periodic netting of settlement payments with respect to multiple different transaction types in the normal course of business. Refer to note 17 on pages 179 to 181 in the 2014 Form 10-K for information on offsetting arrangements and our related accounting policy.
	As of March 31, 2015 and December 31, 2014, the fair value of securities received as collateral where we are permitted to transfer or re-pledge the securities totaled $11.48 billion and $2.60 billion, respectively, and the fair value of the portion that had been transferred or re-pledged as of the same date was $186 million and $125 million, respectively.
	The following tables present information about the offsetting of assets related to derivative contracts and secured financing transactions, as of the dates indicated:
	Assets:	31-Mar-15								31-Dec-14
	(In millions)	Gross Amounts of Recognized Assets(1)		Gross Amounts Offset in Statement of Condition(2)			Net Amounts of Assets Presented in Statement of Condition			Gross Amounts of Recognized Assets(1)		Gross Amounts Offset in Statement of Condition(2)			Net Amounts of Assets Presented in Statement of Condition
	Derivatives:
	Foreign exchange contracts	$	16,116	$	(7,730	)	$	8,386		$	15,135	$	(6,275	)	$	8,860
	Interest-rate contracts	141		(14		)	127			77		(21		)	56
	Other derivative contracts	3		(2		)	1			2		(1		)	1
	Cash collateral netting	—		(466		)	(466		)	—		(983		)	(983		)
	Total derivatives	$	16,260	$	(8,212	)	$	8,048		$	15,214	$	(7,280	)	$	7,934
	Other financial instruments:
	Resale agreements and securities borrowing(3)	$	62,587	$	(31,407	)	$	31,180		$	47,488	$	(29,157	)	$	18,331
	Total derivatives and other financial instruments	$	78,847	$	(39,619	)	$	39,228		$	62,702	$	(36,437	)	$	26,265
	(1) Amounts include all transactions regardless of whether or not they are subject to an enforceable netting arrangement.
	(2) Amounts subject to netting arrangements which have been determined to be legally enforceable.
	(3) Included in the $31,180 million as of March 31, 2015 were $11,331 million of resale agreements and $19,849 million of collateral provided related to securities borrowing. Included in the $18,331 million as of December 31, 2014 were $2,390 million of resale agreements and $15,941 million of collateral provided related to securities borrowing. Resale agreements and collateral provided related to securities borrowing were recorded in securities purchased under resale agreements and other assets, respectively, in our consolidated statement of condition. Refer to note 7 for additional information with respect to principal securities finance transactions.
		31-Mar-15										31-Dec-14
				Gross Amounts Not Offset in Statement of Condition(1)											Gross Amounts Not Offset in Statement of Condition(1)
	(In millions)	Net Amount of Assets Presented in Statement of Condition		Counterparty Netting			Collateral Received			Net Amount(2)		Net Amount of Assets Presented in Statement of Condition			Counterparty Netting			Collateral Received			Net Amount(2)
	Derivatives	$	8,048	$	—		$	(1,442	)	$	6,606	$	7,934		$	—		$	(1,490	)	$	6,444
	Resale agreements and securities borrowing	31,180		(283		)	(30,842		)	55		18,331			(128		)	(18,157		)	46
	Total	$	39,228	$	(283	)	$	(32,284	)	$	6,661	$	26,265		$	(128	)	$	(19,647	)	$	6,490
	(1) Amounts subject to netting arrangements which have been determined to be legally enforceable.
	(2) Includes amounts secured by collateral not determined to be subject to enforceable netting arrangements.
	The following tables present information about the offsetting of liabilities related to derivative contracts and secured financing transactions, as of the dates indicated:
	Liabilities:	31-Mar-15								31-Dec-14
	(In millions)	Gross Amounts of Recognized Liabilities(1)		Gross Amounts Offset in Statement of Condition(2)			Net Amounts of Liabilities Presented in Statement of Condition			Gross Amounts of Recognized Liabilities(1)		Gross Amounts Offset in Statement of Condition(2)			Net Amounts of Liabilities Presented in Statement of Condition
	Derivatives:
	Foreign exchange contracts	$	17,053	$	(7,730	)	$	9,323		$	14,925	$	(6,275	)	$	8,650
	Interest-rate contracts	232		(14		)	218			239		(20		)	219
	Other derivative contracts	112		(2		)	110			70		(1		)	69
	Cash collateral netting	—		(2,661		)	(2,661		)	—		(2,630		)	(2,630		)
	Total derivatives	$	17,397	$	(10,407	)	$	6,990		$	15,234	$	(8,926	)	$	6,308
	Other financial instruments:
	Repurchase agreements and securities lending(3)	$	48,718	$	(31,407	)	$	17,311		$	44,562	$	(29,157	)	$	15,405
	Total derivatives and other financial instruments	$	66,115	$	(41,814	)	$	24,301		$	59,796	$	(38,083	)	$	21,713
	(1) Amounts include all transactions regardless of whether or not they are subject to an enforceable netting arrangement.
	(2) Amounts subject to netting arrangements which have been determined to be legally enforceable.
	(3) Included in the $17,311 million as of March 31, 2015 were $10,158 million of repurchase agreements and $7,153 million of collateral received related to securities lending. Included in the $15,405 million as of December 31, 2014 were $8,925 million of repurchase agreements and $6,480 million of collateral received related to securities lending. Repurchase agreements and collateral received related to securities lending were recorded in securities sold under repurchase agreements and accrued expenses and other liabilities, respectively, in our consolidated statement of condition. Refer to note 7 for additional information with respect to principal securities finance transactions.
		31-Mar-15										31-Dec-14
				Gross Amounts Not Offset in Statement of Condition(1)											Gross Amounts Not Offset in Statement of Condition(1)
	(In millions)	Net Amount of Liabilities Presented in Statement of Condition		Counterparty Netting			Collateral Provided			Net Amount(2)		Net Amount of Liabilities Presented in Statement of Condition			Counterparty Netting			Collateral Provided			Net Amount(2)
	Derivatives	$	6,990	$	—		$	(110	)	$	6,880	$	6,308		$	—		$	(19	)	$	6,289
	Repurchase agreements and securities lending	17,311		(283		)	(15,274		)	1,754		15,405			(128		)	(13,872		)	1,405
	Total	$	24,301	$	(283	)	$	(15,384	)	$	8,634	$	21,713		$	(128	)	$	(13,891	)	$	7,694
	(1) Amounts subject to netting arrangements which have been determined to be legally enforceable.
	(2) Includes amounts secured by collateral not determined to be subject to enforceable netting arrangements.

Net_Interest_Revenue

Net Interest Revenue	3 Months Ended
	Mar. 31, 2015
Net Interest Revenue [Abstract]
Net Interest Revenue	Net Interest Revenue
	The following table presents the components of interest revenue and interest expense, and related net interest revenue, for the periods indicated:
		Three Months Ended March 31,
	(In millions)	2015		2014
	Interest revenue:
	Deposits with banks	$	54	$	34
	Investment securities:
	U.S. Treasury and federal agencies	183		163
	State and political subdivisions	58		71
	Other investments	259		319
	Securities purchased under resale agreements	11		9
	Loans and leases	74		58
	Other interest-earning assets	3		1
	Total interest revenue	642		655
	Interest expense:
	Deposits	26		15
	Short-term borrowings	1		15
	Long-term debt	62		63
	Other interest-bearing liabilities	7		7
	Total interest expense	96		100
	Net interest revenue	$	546	$	555

Expenses

Expenses	3 Months Ended
	Mar. 31, 2015
Other Expenses [Abstract]
Expenses	Expenses
	Acquisition and Restructuring Costs:
	The following table presents net acquisition and restructuring costs recorded in the periods indicated:
		Three Months Ended March 31,
	(In millions)	2015			2014
	Acquisition costs	$	5		$	21
	Restructuring charges, net	1			12
	Total acquisition and restructuring costs	$	6		$	33
	Acquisition Costs
	Acquisition costs recorded in the three months ended March 31, 2015 and 2014 were related to previously disclosed acquisitions.
	Restructuring Charges
	In the three months ended March 31, 2015, we recorded net restructuring charges of $1 million compared to $12 million in the three months ended March 31, 2014. The amounts recorded mainly related to our recently completed Business Operations and Information Technology Transformation program.
	Aggregate Restructuring-Related Accrual Activity
	The following table presents aggregate activity associated with accruals that resulted from the charges associated with the recently completed Business Operations and Information Technology Transformation program:
	(In millions)	Employee-			Real Estate Consolidation			Asset and Other Write-Offs			Total
		Related
		Costs
	Balance as of December 31, 2014	$	40		$	24		$	7		$	71
	Additional accruals for Business Operations and Information Technology Transformation program	(3		)	—			—			(3		)
	Additional accruals for 2012 expense control measures	—			—			4			4
	Payments and adjustments	(10		)	(3		)	(5		)	(18		)
	Balance as of March 31, 2015	$	27		$	21		$	6		$	54

Earnings_Per_Common_Share

Earnings Per Common Share	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Earnings Per Common Share	Earnings Per Common Share
	Basic earnings per share, or EPS, is calculated pursuant to the “two-class” method, by dividing net income available to common shareholders by the weighted-average common shares outstanding during the period. Diluted EPS is calculated pursuant to the two-class method, by dividing net income available to common shareholders by the total weighted-average number of common shares outstanding for the period plus the shares representing the dilutive effect of common stock options and other equity-based awards. The effect of common stock options and other equity-based awards is excluded from the calculation of diluted EPS in periods in which their effect would be anti-dilutive.
	The two-class method requires the allocation of undistributed net income between common and participating shareholders. Net income available to common shareholders, presented separately in our consolidated statement of income, is the basis for the calculation of both basic and diluted EPS. Participating securities are composed of unvested restricted stock and fully vested deferred director stock awards, which are equity-based awards that contain non-forfeitable rights to dividends, and are considered to participate with the common stock in undistributed earnings.
	The following tables present the computation of basic and diluted earnings per common share for the periods indicated:
		Three Months Ended March 31,
	(Dollars in millions, except per share amounts)	2015			2014
	Net income	$	409		$	363
	Less:
	Preferred stock dividends	(31		)	(6		)
	Dividends and undistributed earnings allocated to participating securities(1)	(1		)	(1		)
	Net income available to common shareholders	$	377		$	356
	Average common shares outstanding (in thousands):
	Basic average common shares	412,225			430,621
	Effect of dilutive securities: common stock options and common stock awards	6,525			8,194
	Diluted average common shares	418,750			438,815
	Anti-dilutive securities(2)	791			1,504
	Earnings per Common Share:
	Basic	$	0.91		$	0.83
	Diluted(3)	0.9			0.81
	(1) Represents the portion of net income available to common equity allocated to participating securities, composed of fully vested deferred director stock and unvested restricted stock that contain non-forfeitable rights to dividends during the vesting period on a basis equivalent to dividends paid to common shareholders.
	(2) Represents common stock options and other equity-based awards outstanding but not included in the computation of diluted average common shares, because their effect was anti-dilutive.
	(3) Calculations reflect allocation of earnings to participating securities using the two-class method, as this computation is more dilutive than the treasury stock method.

Line_of_Business_Information

Line of Business Information	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Line of Business Information	Line of Business Information
	We have two lines of business: Investment Servicing and Investment Management. The results of operations for these lines of business are not necessarily comparable with those of other companies, including companies in the financial services industry. Information about our two lines of business, as well as revenues, expenses and capital allocation methodologies associated with them, is provided in note 24 to the consolidated financial statements included in the 2014 Form 10-K.
	The following is a summary of our line-of-business results for the periods indicated. The “Other” column represents costs incurred that are not allocated to a specific line of business, including certain severance and restructuring costs, acquisition costs and certain provisions for legal contingencies.
		Three Months Ended March 31,
		Investment						Investment						Other						Total
		Servicing						Management
		2015			2014			2015			2014			2015			2014			2015			2014
	(Dollars in millions,
	except where otherwise noted)
	Servicing fees	$	1,273		$	1,238		$	—		$	—		$	—		$	—		$	1,273		$	1,238
	Management fees	—			—			301			292			—			—			301			292
	Trading services	315			241			9			12			—			—			324			253
	Securities finance	101			85			—			—			—			—			101			85
	Processing fees and other	59			55			2			1			—			—			61			56
	Total fee revenue	1,748			1,619			312			305			—			—			2,060			1,924
	Net interest revenue	545			551			1			4			—			—			546			555
	Gains (losses) related to investment securities, net	(1		)	6			—			—			—			—			(1		)	6
	Total revenue	2,292			2,176			313			309			—			—			2,605			2,485
	Provision for loan losses	4			2			—			—			—			—			4			2
	Total expenses	1,836			1,672			256			245			5			111			2,097			2,028
	Income before income tax expense	$	452		$	502		$	57		$	64		$	(5	)	$	(111	)	$	504		$	455
	Pre-tax margin	20		%	23		%	18		%	21		%							19		%	18		%

NonUS_Activities

Non-U.S. Activities	3 Months Ended
	Mar. 31, 2015
Segments, Geographical Areas [Abstract]
Non-U.S. Activities	Non-U.S. Activities
	We generally define our non-U.S. activities as those revenue-producing business activities that arise from clients domiciled outside the U.S. Due to the integrated nature of our business, precise segregation of our U.S. and non-U.S. activities is not possible. Subjective estimates and other judgments are applied to quantify the financial results and assets related to our non-U.S. activities, including our application of funds transfer pricing, our asset-and-liability management policies and our allocation of certain indirect corporate expenses. Interest expense allocations are based on our internal funds transfer pricing methodology.
	The following table presents our non-U.S. financial results for the periods indicated.
		Three Months Ended March 31,
	(In millions)	2015			2014
	Total fee revenue	$	857		$	788
	Net interest revenue	291			312
	Gains (losses) related to investment securities, net	(1		)	6
	Total revenue	1,147			1,106
	Expenses	805			852
	Income before income taxes	342			254
	Income tax expense	78			61
	Net income	$	264		$	193
	The following table presents the significant components of our non-U.S. assets as of the dates indicated, based on the domicile of the underlying counterparties:
	(In millions)	March 31, 2015			December 31, 2014
	Interest-bearing deposits with banks	$	26,893		$	17,382
	Investment securities	26,863			29,060
	Other assets	13,948			13,577
	Total non-U.S. assets	$	67,704		$	60,019

Basis_of_Presentation_Policies

Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation	The accounting and financial reporting policies of State Street Corporation conform to U.S. generally accepted accounting principles, referred to as GAAP. State Street Corporation, the parent company, is a financial holding company headquartered in Boston, Massachusetts. Unless otherwise indicated or unless the context requires otherwise, all references in these notes to consolidated financial statements to “State Street,” “we,” “us,” “our” or similar references mean State Street Corporation and its subsidiaries on a consolidated basis. Our principal banking subsidiary is State Street Bank and Trust Company, or State Street Bank.
	The accompanying Consolidated Financial Statements should be read in conjunction with the financial and risk factor information included in our 2014 Annual Report on Form 10-K (2014 Form 10-K), which we previously filed with the Securities and Exchange Commission, or SEC.
	The consolidated financial statements accompanying these condensed notes are unaudited. In the opinion of management, all adjustments, consisting only of normal recurring adjustments, which are necessary for a fair statement of the consolidated results of operations in these financial statements, have been made. Certain previously reported amounts presented in this Form 10-Q have been reclassified to conform to current-period presentation. Events occurring subsequent to the date of our consolidated statement of condition were evaluated for potential recognition or disclosure in our consolidated financial statements through the date we filed this Form 10-Q with the SEC.
	The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions in the application of certain of our significant accounting policies that may materially affect the reported amounts of assets, liabilities, equity, revenue, and expenses. As a result of unanticipated events or circumstances, actual results could differ from those estimates. These accounting estimates reflect the best judgment of management, but actual results could differ.
	Our consolidated statement of condition as of December 31, 2014 included in the accompanying consolidated financial statements was derived from the audited financial statements as of that date, but does not include all notes required by GAAP for a complete set of consolidated financial statements.
Recent Accounting Developments	Recent Accounting Developments:
	In February 2015, the Financial Accounting Standards Board, or FASB, issued an amendment to GAAP to remove the concept of "extraordinary items," which are defined as items that are unusual and infrequent in nature. The amendment, which allows for early adoption, is effective for State Street beginning on January 1, 2016. Our adoption of this amendment is not expected to have a material effect on our consolidated financial statements.
	In February 2015, the FASB issued an amendment to GAAP that updates the consolidation model used to evaluate whether a legal entity is required to be consolidated. The amendment, which allows for early adoption, is effective for State Street beginning on January 1, 2016, and may be applied retrospectively or via a modified retrospective approach. We are currently assessing the potential impact of this amendment on our consolidated financial statements.
	In April 2015, the FASB issued an amendment to GAAP that requires debt issuance costs to be presented in the consolidated balance sheet as a direct deduction from the carrying value of the associated debt liability, consistent with the presentation of a debt discount. The amendment, which allows for early adoption, is effective for State Street beginning on January 1, 2016. Our debt issuance costs that are currently classified as deferred credits and have a balance of approximately $28 million as of March 31, 2015 will be reclassified as contra liabilities upon adoption.
	In April 2015, the FASB issued an amendment to GAAP which will assist entities in evaluating the accounting for fees paid by a customer in a cloud computing arrangement. The amendment, which allows for early adoption, is effective for State Street beginning on January 1, 2016. Our adoption of this amendment is not expected to have a material effect on our consolidated financial statements.
Tax-Exempt Investment Program	Tax-Exempt Investment Program:
	In the normal course of our business, we structure and sell certificated interests in pools of tax-exempt investment-grade assets, principally to our mutual fund clients. We structure these pools as partnership trusts, and the assets and liabilities of the trusts are recorded in our consolidated statement of condition as investment securities available for sale and other short-term borrowings. As of March 31, 2015 and December 31, 2014, we carried investment securities available for sale, composed of securities related to state and political subdivisions, with a fair value of $2.24 billion and $2.27 billion, respectively, and other short-term borrowings of $1.84 billion and $1.87 billion, respectively, in our consolidated statement of condition in connection with these trusts. The interest revenue and interest expense generated by the investments and certificated interests, respectively, are recorded as components of net interest revenue when earned or incurred.
	The trusts had a weighted-average life of approximately 5.7 years as of March 31, 2015, compared to approximately 5.9 years as of December 31, 2014.
	Under separate legal agreements, we provide standby bond-purchase agreements to these trusts and, with respect to certain securities, letters of credit. Our commitments to the trusts under these standby bond-purchase agreements and letters of credit totaled $1.88 billion and $669 million, respectively, as of March 31, 2015, none of which was utilized as of that date.

Fair_Value_Tables

Fair Value (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following tables present information with respect to our financial assets and liabilities carried at fair value in our consolidated statement of condition on a recurring basis as of the dates indicated. No transfers of financial assets or liabilities between levels 1 and 2 occurred in the three months ended March 31, 2015 or the year ended December 31, 2014.
		Fair-Value Measurements on a Recurring Basis
		as of March 31, 2015
	(In millions)	Quoted Market			Pricing Methods			Pricing Methods				Impact of Netting(1)			Total Net
		Prices in Active			with Significant			with Significant							Carrying Value
		Markets			Observable			Unobservable							in Consolidated
		(Level 1)			Market Inputs			Market Inputs							Statement of
					(Level 2)			(Level 3)							Condition
	Assets:
	Trading account assets:
	U.S. government securities	$	20		$	—		$	—						$	20
	Non-U.S. government securities	569			—			—							569
	Other	20			536			—							556
	Total trading account assets	609			536			—							1,145
	Investment securities available for sale:
	U.S. Treasury and federal agencies:
	Direct obligations	12,418			578			—							12,996
	Mortgage-backed securities	—			21,046			—							21,046
	Asset-backed securities:
	Student loans	—			11,807			257							12,064
	Credit cards	—			2,917			—							2,917
	Sub-prime	—			911			—							911
	Other(2)	—			395			3,633							4,028
	Total asset-backed securities	—			16,030			3,890							19,920
	Non-U.S. debt securities:
	Mortgage-backed securities	—			8,621			43							8,664
	Asset-backed securities	—			3,133			228							3,361
	Government securities	—			3,811			—							3,811
	Other(3)	—			4,789			442							5,231
	Total non-U.S. debt securities	—			20,354			713							21,067
	State and political subdivisions	—			11,012			37							11,049
	Collateralized mortgage obligations	—			5,308			522							5,830
	Other U.S. debt securities	—			4,064			9							4,073
	U.S. equity securities	—			39			—							39
	Non-U.S. equity securities	—			2			—							2
	U.S. money-market mutual funds	—			582			—							582
	Non-U.S. money-market mutual funds	—			8			—							8
	Total investment securities available for sale	12,418			79,023			5,171							96,612
	Other assets:
	Derivative instruments:
	Foreign exchange contracts	—			15,931			185				$	(8,087	)	8,029
	Interest-rate contracts	—			141			—				(123		)	18
	Other derivative contracts	—			3			—				(2		)	1
	Total derivative instruments	—			16,075			185				(8,212		)	8,048
	Total assets carried at fair value	$	13,027		$	95,634		$	5,356			$	(8,212	)	$	105,805
	Liabilities:
	Accrued expenses and other liabilities:
	Trading account liabilities:
	Other	$	4		$	—		$	—			$	—		$	4
	Derivative instruments:
	Foreign exchange contracts	—			16,881			172				(10,361		)	6,692
	Interest-rate contracts	—			232			—				(44		)	188
	Other derivative contracts	—			103			9				(2		)	110
	Total derivative instruments	—			17,216			181				(10,407		)	6,990
	Total liabilities carried at fair value	$	4		$	17,216		$	181			$	(10,407	)	$	6,994
	(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 $466 million and $2.66 billion, respectively, for cash collateral received from and provided to derivative counterparties.
	(2) As of March 31, 2015 the fair value of other asset-backed securities was primarily composed of $3.6 billion of collateralized loan obligations and approximately $348 million of automobile loan securities.
	(3) As of March 31, 2015 the fair value of other non-U.S. debt securities was primarily composed of $3.3 billion of covered bonds and $1.1 billion of corporate bonds.
		Fair-Value Measurements on a Recurring Basis
		as of December 31, 2014
	(In millions)	Quoted Market			Pricing Methods			Pricing Methods				Impact of Netting(1)			Total Net
		Prices in Active			with Significant			with Significant							Carrying Value
		Markets			Observable			Unobservable							in Consolidated
		(Level 1)			Market Inputs			Market Inputs							Statement of
			(Level 2)			(Level 3)			Condition
Assets:
Trading account assets:
U.S. government securities	$	20		$	—		$	—						$	20
Non-U.S. government securities	378			—			—							378
Other	20			506			—							526
Total trading account assets	418			506			—							924
Investment securities available for sale:
U.S. Treasury and federal agencies:
Direct obligations	10,056			599			—							10,655
Mortgage-backed securities	—			20,714			—							20,714
Asset-backed securities:
Student loans	—			12,201			259							12,460
Credit cards	—			3,053			—							3,053
Sub-prime	—			951			—							951
Other(2)	—			365			3,780							4,145
Total asset-backed securities	—			16,570			4,039							20,609
Non-U.S. debt securities:
Mortgage-backed securities	—			9,606			—							9,606
Asset-backed securities	—			2,931			295							3,226
Government securities	—			3,909			—							3,909
Other(3)	—			5,057			371							5,428
Total non-U.S. debt securities	—			21,503			666							22,169
State and political subdivisions	—			10,782			38							10,820
Collateralized mortgage obligations	—			4,725			614							5,339
Other U.S. debt securities	—			4,100			9							4,109
U.S. equity securities	—			39			—							39
Non-U.S. equity securities	—			2			—							2
U.S. money-market mutual funds	—			449			—							449
Non-U.S. money-market mutual funds	—			8			—							8
Total investment securities available for sale	10,056			79,491			5,366							94,913
Other assets:
Derivatives instruments:
Foreign exchange contracts	—			15,054			81				$	(7,211	)	7,924
Interest-rate contracts	—			77			—				(68		)	9
Other derivative contracts	—			2			—				(1		)	1
Total derivative instruments	—			15,133			81				(7,280		)	7,934
Total assets carried at fair value	$	10,474		$	95,130		$	5,447			$	(7,280	)	$	103,771
Liabilities:
Accrued expenses and other liabilities:
Derivative instruments:
Foreign exchange contracts	$	—		$	14,851		$	74			$	(8,879	)	$	6,046
Interest-rate contracts	—			239			—				(46		)	193
Other derivative contracts	—			61			9				(1		)	69
Total derivative instruments	—			15,151			83				(8,926		)	6,308
Total liabilities carried at fair value	$	—		$	15,151		$	83			$	(8,926	)	$	6,308
(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 $983 million and $2.63 billion, respectively, for cash collateral received from and provided to derivative counterparties.
(2) As of December 31, 2014, the fair value of other asset-backed securities was primarily composed of $3.8 billion of collateralized loan obligations and approximately $315 million of automobile loan securities.
(3) As of December 31, 2014, the fair value of other non-U.S. debt securities was primarily composed of $3.3 billion of covered bonds and $1.2 billion of corporate bonds.
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation	The following tables present activity related to our level-3 financial assets and liabilities during the three months ended March 31, 2015 and 2014, respectively. Transfers into and out of level 3 are reported as of the beginning of the period presented. In the three months ended March 31, 2015 and 2014, transfers out of level 3 were mainly related to certain mortgage- and asset-backed securities, including non-U.S. debt securities, for which fair value was measured using prices for which observable market information became available.
		Fair Value Measurements Using Significant Unobservable Inputs
		Three Months Ended March 31, 2015
		Fair Value  as of			Total Realized and							Purchases			Settlements			Transfers			Fair Value  as of			Change in
		31-Dec-14			Unrealized Gains (Losses)													out of			March 31, 2015(1)			Unrealized
																		Level 3						Gains
																								(Losses)
																								Related to
																								Financial
																								Instruments
																								Held as of
																								March 31,
	(In millions)				Recorded			Recorded																2015
					in			in Other
					Revenue			Comprehensive
								Income
	Assets:
	Investment securities available for sale:
	Asset-backed securities:
	Student loans	$	259		$	—		$	1			$	—		$	(3	)	$	—		$	257
	Other	3,780			12			(12		)		—			(147		)	—			3,633
	Total asset-backed securities	4,039			12			(11		)		—			(150		)	—			3,890
	Non-U.S. debt securities:
	Mortgage-backed securities	—			—			—				43			—			—			43
	Asset-backed securities	295			1			—				—			(68		)	—			228
	Other	371			—			1				111			(41		)	—			442
	Total non-U.S. debt securities	666			1			1				154			(109		)	—			713
	State and political subdivisions	38			—			(1		)		—			—			—			37
	Collateralized mortgage obligations	614			—			—				293			(36		)	(349		)	522
	Other U.S. debt securities	9			—			—				—			—			—			9
	Total investment securities available for sale	5,366			13			(11		)		447			(295		)	(349		)	5,171
	Other assets:
	Derivative instruments:
	Derivative instruments, Foreign exchange contracts	81			131			—				36			(63		)	—			185			$	107
	Total derivative instruments	81			131			—				36			(63		)	—			185			107
	Total assets carried at fair value	$	5,447		$	144		$	(11	)		$	483		$	(358	)	$	(349	)	$	5,356		$	107
		Fair-Value Measurements Using Significant Unobservable Inputs
		Three Months Ended March 31, 2014
		Fair Value  as of December 31,			Total Realized and							Purchases			Sales			Settlements			Transfers			Fair Value  as of		Change in
		2013			Unrealized Gains (Losses)																out of			March 31, 2014(1)		Unrealized
																					Level 3					Gains
																										(Losses)
																										Related to
																										Financial
																										Instruments
																										Held as of
																										March 31,
	(In millions)				Recorded			Recorded																		2014
					in			in Other
					Revenue			Comprehensive
								Income
	Assets:
	Investment securities available for sale:
	U.S. Treasury and federal agencies, mortgage-backed securities	$	716		$	—		$	—			$	—		$	—		$	(5	)	$	(611	)	$	100
	Asset-backed securities:
	Student loans	423			1			1				—			—			(13		)	(79		)	333
	Credit cards	24			—			—				—			—			(24		)	—			—
	Other	4,532			15			(4		)		6			—			(245		)	—			4,304
	Total asset-backed securities	4,979			16			(3		)		6			—			(282		)	(79		)	4,637
	Non-U.S. debt securities:
	Mortgage-backed securities	375			—			—				—			—			—			(375		)	—
	Asset-backed securities	798			2			(1		)		—			—			(63		)	(124		)	612
	Other	464			—			(1		)		—			(1		)	—			—			462
	Total non-U.S. debt securities	1,637			2			(2		)		—			(1		)	(63		)	(499		)	1,074
State and political subdivisions	43			—			—				—			—			(1		)	—			42
Collateralized mortgage obligations	162			—			—				80			(6		)	(6		)	(28		)	202
Other U.S. debt securities	8			—			—				—			—			—			—			8
Total investment securities available for sale	7,545			18			(5		)		86			(7		)	(357		)	(1,217		)	6,063
Other assets:
Derivative instruments:
Derivative instruments, Foreign exchange contracts	19			(11		)	—				7			—			(9		)	—			6		$	(7	)
Total derivative instruments	19			(11		)	—				7			—			(9		)	—			6		(7		)
Total assets carried at fair value	$	7,564		$	7		$	(5	)		$	93		$	(7	)	$	(366	)	$	(1,217	)	$	6,069	$	(7	)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation
		Fair-Value Measurements Using Significant Unobservable Inputs
		Three Months Ended March 31, 2015
		Fair Value  as of			Total Realized and			Issuances				Settlements			Fair Value  as of			Change in
		31-Dec-14			Unrealized (Gains) Losses										March 31, 2015(2)			Unrealized
																		(Gains)
																		Losses Related to
																		Financial
																		Instruments
																		Held as of
																		March 31,
	(In millions)				Recorded													2015
					in
					Revenue
	Liabilities:
	Accrued expenses and other liabilities:
	Derivative instruments:
	Foreign exchange contracts	$	74		$	109		$	37			$	(48	)	$	172		$	93
	Other	9			—			—				—			9
	Total derivative instruments	83			109			37				(48		)	181			93
	Total liabilities carried at fair value	$	83		$	109		$	37			$	(48	)	$	181		$	93
	(1) There were no transfers of assets into level 3 during the three months ended March 31, 2015.
	(2) There were no transfers of liabilities into or out of level 3 during the three months ended March 31, 2015.
		Fair-Value Measurements Using Significant Unobservable Inputs
		Three Months Ended March 31, 2014
		Fair Value  as of December 31,			Total Realized and			Issuances				Settlements			Fair Value  as of			Change in
		2013			Unrealized (Gains) Losses										March 31, 2014(2)			Unrealized
																		(Gains)
																		Losses
																		Related to
																		Financial
																		Instruments
																		Held as of
																		March 31,
	(In millions)				Recorded													2014
					in
					Revenue
	Liabilities:
	Accrued expenses and other liabilities:
	Derivative instruments:
	Foreign exchange contracts	$	17		$	(10	)	$	7			$	(6	)	$	8		$	(5	)
	Other	9			—			—				—			9			—
	Total derivative instruments	26			(10		)	7				(6		)	17			(5		)
	Total liabilities carried at fair value	$	26		$	(10	)	$	7			$	(6	)	$	17		$	(5	)
	(1) There were no transfers of assets into level 3 during the three months ended March 31, 2014.
	(2) There were no transfers of liabilities into or out of level 3 in the three months ended March 31, 2014.
Level 3 Total Realized And Unrealized Gains And Losses Recorded In Revenue	The following table presents total realized and unrealized gains and losses for our level-3 financial assets and liabilities and where they are presented in our consolidated statement of income for the periods indicated:
		Three Months Ended March 31,
		Total Realized and						Change in
		Unrealized Gains						Unrealized Gains
		(Losses) Recorded						(Losses) Related to
		in Revenue						Financial
								Instruments Held as of
								March 31,
	(In millions)	2015			2014			2015				2014
	Fee revenue:
	Trading services	$	22		$	(1	)	$	14			$	(2	)
	Total fee revenue	22			(1		)	14				(2		)
	Net interest revenue	13			18			—				—
	Total revenue	$	35		$	17		$	14			$	(2	)
Fair Value Inputs, Assets and Liabilities, Quantitative Information	The following table presents quantitative information, as of the dates indicated, about the valuation techniques and significant unobservable inputs used in the valuation of our level-3 financial assets and liabilities measured at fair value on a recurring basis for which we use internally-developed pricing models. The significant unobservable inputs for our level-3 financial assets and liabilities whose fair value is measured using pricing information from non-binding broker or dealer quotes are not included in the table, as the specific inputs applied are not provided by the broker/dealer.
			Quantitative Information about Level-3 Fair-Value Measurements
			Fair Value										Weighted-Average
	(Dollars in millions)		As of March 31, 2015			As of December 31, 2014			Valuation Technique		Significant		As of March 31, 2015		As of December 31, 2014
											Unobservable Input(1)
	Significant unobservable inputs readily available to State Street:
	Assets:
	Asset-backed securities, other		$	54		$	59		Discounted cash flows		Credit spread		0.2	%	0.2	%
	State and political subdivisions		37			38			Discounted cash flows		Credit spread		2.2		2.1
	Derivative instruments, foreign exchange contracts		185			81			Option model		Volatility		10.8		9.1
	Total		$	276		$	178
	Liabilities:
	Derivative instruments, foreign exchange contracts		$	172		$	74		Option model		Volatility		11.3		9
	Derivative instruments, other(2)		9			9			Discounted cash flows		Participant redemptions		5		5.2
	Total		$	181		$	83
	(1) Significant changes in these unobservable inputs would result in significant changes in fair value measure.
	(2) Relates to stable value wrap contracts; refer to the sensitivity discussion following the tables presented below, and to note 7.
Schedule of Availability of Significant Unobservable Inputs by Balance Sheet Classification	The following tables present information with respect to the composition of our level-3 financial assets and liabilities, by availability of significant unobservable inputs, as of the dates indicated:
	31-Mar-15		Significant Unobservable Inputs Readily Available to State Street(1)			Significant Unobservable Inputs Not Developed by State Street and Not Readily Available(2)			Total Assets and Liabilities with Significant Unobservable Inputs
	(In millions)
	Assets:
	Asset-backed securities, student loans		$	—		$	257		$	257
	Asset-backed securities, other		54			3,579			3,633
	Non-U.S. debt securities, mortgage-backed securities		—			43			43
	Non-U.S. debt securities, asset-backed securities		—			228			228
	Non-U.S. debt securities, other					442			442
	State and political subdivisions		37			—			37
	Collateralized mortgage obligations		—			522			522
	Other U.S. debt securities		—			9			9
	Derivative instruments, foreign exchange contracts		185			—			185
	Total		$	276		$	5,080		$	5,356
	Liabilities:
	Derivative instruments, foreign exchange contracts		$	172		$	—		$	172
	Derivative instruments, other		9			—			9
	Total		$	181		$	—		$	181
	(1) Information with respect to these model-priced financial assets and liabilities is provided above in a separate table.
	(2) Fair value for these financial assets is measured using non-binding broker or dealer quotes.
	31-Dec-14		Significant Unobservable Inputs Readily Available to State Street(1)			Significant Unobservable Inputs Not Developed by State Street and Not Readily Available(2)			Total Assets and Liabilities with Significant Unobservable Inputs
	(In millions)
	Assets:
	Asset-backed securities, student loans		$	—		$	259		$	259
	Asset-backed securities, other		59			3,721			3,780
	Non-U.S. debt securities, asset-backed securities		—			295			295
	Non-U.S. debt securities, other		—			371			371
	State and political subdivisions		38			—			38
	Collateralized mortgage obligations		—			614			614
	Other U.S. debt securities		—			9			9
	Derivative instruments, foreign exchange contracts		81			—			81
	Total		$	178		$	5,269		$	5,447
	Liabilities:
	Derivative instruments, foreign exchange contracts		$	74		$	—		$	74
	Derivative instruments, other		9			—			9
	Total		$	83		$	—		$	83
	(1) Information with respect to these model-priced financial assets and liabilities is provided above in a separate table.
	(2) Fair value for these financial assets is measured using non-binding broker or dealer quotes.
Carrying Value and Estimated Fair Value of Financial Instruments by Fair Value Hierarchy	The following tables present the reported amounts and estimated fair values of the financial assets and liabilities not carried at fair value on a recurring basis, as they would be categorized within the fair-value hierarchy, as of the dates indicated.
									Fair-Value Hierarchy
	31-Mar-15		Reported Amount			Estimated Fair Value			Quoted Market Prices in Active Markets (Level 1)				Pricing Methods with Significant Observable Market Inputs (Level 2)			Pricing Methods with Significant Unobservable Market Inputs (Level 3)
	(In millions)
	Financial Assets:
	Cash and due from banks		$	3,149		$	3,149		$	3,149			$	—		$	—
	Interest-bearing deposits with banks		83,398			83,398			—				83,398			—
	Securities purchased under resale agreements		11,331			11,331			—				11,331			—
	Investment securities held to maturity		16,245			16,417			—				16,417			—
	Net loans (excluding leases)		17,344			17,339			—				17,177			162
	Financial Liabilities:
	Deposits:
	Noninterest-bearing		$	72,704		$	72,704		$	—			$	72,704		$	—
	Interest-bearing - U.S.		30,769			30,769			—				30,769			—
	Interest-bearing - non-U.S.		107,879			107,879			—				107,879			—
	Securities sold under repurchase agreements		10,158			10,158			—				10,158			—
	Federal funds purchased		17			17			—				17			—
	Other short-term borrowings		4,346			4,346			—				4,346			—
	Long-term debt		9,174			9,432			—				8,592			840
									Fair-Value Hierarchy
	31-Dec-14		Reported Amount			Estimated Fair Value			Quoted Market Prices in Active Markets (Level 1)				Pricing Methods with Significant Observable Market Inputs (Level 2)			Pricing Methods with Significant Unobservable Market Inputs (Level 3)
	(In millions)
	Financial Assets:
	Cash and due from banks		$	1,855		$	1,855		$	1,855			$	—		$	—
	Interest-bearing deposits with banks		93,523			93,523			—				93,523			—
	Securities purchased under resale agreements		2,390			2,390			—				2,390			—
	Investment securities held to maturity		17,723			17,842			—				17,842			—
	Net loans (excluding leases)		17,158			17,131			—				16,964			167
	Financial Liabilities:
	Deposits:
	Noninterest-bearing		$	70,490		$	70,490		$	—			$	70,490		$	—
	Interest-bearing - U.S.		33,012			33,012			—				33,012			—
	Interest-bearing - non-U.S.		105,538			105,538			—				105,538			—
	Securities sold under repurchase agreements		8,925			8,925			—				8,925			—
	Federal funds purchased		21			21			—				21			—
	Other short-term borrowings		4,381			4,381			—				4,381			—
	Long-term debt		10,042			10,229			—				9,382			847

Investment_Securities_Tables

Investment Securities (Tables)	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Schedule of Marketable Securities	The following table presents the amortized cost and fair value, and associated unrealized gains and losses, of investment securities as of the dates indicated:
		March 31, 2015										December 31, 2014
		Amortized			Gross					Fair		Amortized		Gross				Fair
		Cost			Unrealized					Value		Cost		Unrealized				Value
	(In millions)				Gains			Losses						Gains		Losses
	Available for sale:
	U.S. Treasury and federal agencies:
	Direct obligations	$	12,803		$	194		$	1	$	12,996	$	10,573	$	83	$	1	$	10,655
	Mortgage-backed securities	20,861			251			66		21,046		20,648		193		127		20,714
	Asset-backed securities:
	Student loans(1)	12,070			107			113		12,064		12,478		106		124		12,460
	Credit cards	2,941			10			34		2,917		3,077		10		34		3,053
	Sub-prime	961			2			52		911		1,005		2		56		951
	Other(2)	3,950			90			12		4,028		4,055		100		10		4,145
	Total asset-backed securities	19,922			209			211		19,920		20,615		218		224		20,609
	Non-U.S. debt securities:
	Mortgage-backed securities	8,522			146			4		8,664		9,442		168		4		9,606
	Asset-backed securities	3,353			9			1		3,361		3,215		11		—		3,226
	Government securities	3,800			11			—		3,811		3,899		10		—		3,909
	Other(3)	5,186			50			5		5,231		5,383		52		7		5,428
	Total non-U.S. debt securities	20,861			216			10		21,067		21,939		241		11		22,169
	State and political subdivisions	10,729			357			37		11,049		10,532		325		37		10,820
	Collateralized mortgage obligations	5,738			99			7		5,830		5,280		71		12		5,339
	Other U.S. debt securities	3,987			94			8		4,073		4,033		88		12		4,109
	U.S. equity securities	31			9			1		39		29		10		—		39
	Non-U.S. equity securities	2			—			—		2		2		—		—		2
	U.S. money-market mutual funds	582			—			—		582		449		—		—		449
	Non-U.S. money-market mutual funds	8			—			—		8		8		—		—		8
	Total	$	95,524		$	1,429		$	341	$	96,612	$	94,108	$	1,229	$	424	$	94,913
	Held to maturity:
	U.S. Treasury and federal agencies:
	Direct obligations	$	5,112		$	—		$	69	$	5,043	$	5,114	$	—	$	147	$	4,967
	Mortgage-backed securities	57			4			—		61		62		4		—		66
	Asset-backed securities:
	Student loans(1)	1,755			3			5		1,753		1,814		2		4		1,812
	Credit cards	897			2			—		899		897		2		—		899
	Other	545			3			—		548		577		3		1		579
	Total asset-backed securities	3,197			8			5		3,200		3,288		7		5		3,290
	Non-U.S. debt securities:
	Mortgage-backed securities	3,275			154			19		3,410		3,787		177		22		3,942
	Asset-backed securities	2,298			11			—		2,309		2,868		14		1		2,881
	Government securities	148			—			—		148		154		—		—		154
	Other	65			—			—		65		72		—		—		72
	Total non-U.S. debt securities	5,786			165			19		5,932		6,881		191		23		7,049
	State and political subdivisions	3			—			—		3		9		—		—		9
	Collateralized mortgage obligations	2,090			96			8		2,178		2,369		107		15		2,461
	Total	$	16,245		$	273		$	101	$	16,417	$	17,723	$	309	$	190	$	17,842
	(1) Substantially composed of securities guaranteed by the federal government with respect to at least 97% of defaulted principal and accrued interest on the underlying loans.
	(2) As of March 31, 2015 and December 31, 2014, the fair value of other asset-backed securities was primarily composed of $3.6 billion and $3.8 billion, respectively, of collateralized loan obligations and approximately $348 million and approximately $315 million, respectively, of automobile loan securities.
	(3) As of both March 31, 2015 and December 31, 2014, the fair value of other non-U.S. debt securities was primarily composed of $3.3 billion of covered bonds and $1.1 billion and $1.2 billion, as of March 31, 2015 and December 31, 2014, respectively, of corporate bonds.
Schedule of Gross Pre-tax Unrealized Losses on Investment Securities	The following tables present the aggregate fair values of investment securities that have been in a continuous unrealized loss position for less than 12 months, and those that have been in a continuous unrealized loss position for 12 months or longer, as of the dates indicated:
		Less than 12 months						12 months or longer				Total
	March 31, 2015	Fair			Gross			Fair		Gross		Fair		Gross
		Value			Unrealized			Value		Unrealized		Value		Unrealized
	(In millions)				Losses					Losses				Losses
	Available for sale:
	U.S. Treasury and federal agencies:
	Direct obligations	$	—		$	—		$	158	$	1	$	158	$	1
	Mortgage-backed securities	1,565			8			4,373		58		5,938		66
	Asset-backed securities:
	Student loans	1,440			13			4,875		100		6,315		113
	Credit cards	—			—			1,287		34		1,287		34
	Sub-prime	—			—			860		52		860		52
	Other	844			5			640		7		1,484		12
	Total asset-backed securities	2,284			18			7,662		193		9,946		211
	Non-U.S. debt securities:
	Mortgage-backed securities	1,097			3			146		1		1,243		4
	Asset-backed securities	499			1			—		—		499		1
	Other	641			2			293		3		934		5
	Total non-U.S. debt securities	2,237			6			439		4		2,676		10
	State and political subdivisions	980			6			776		31		1,756		37
	Collateralized mortgage obligations	747			2			208		5		955		7
	Other U.S. debt securities	—			—			146		8		146		8
	U.S. equity securities	6			1			—		—		6		1
	Total	$	7,819		$	41		$	13,762	$	300	$	21,581	$	341
	Held to maturity:
	U.S. Treasury and federal agencies:
	Direct obligations	$	2,062		$	13		$	2,981	$	56	$	5,043	$	69
	Asset-backed securities:
	Student loans	631			3			232		2		863		5
	Total asset-backed securities	631			3			232		2		863		5
	Non-U.S. mortgage-backed securities:
	Mortgage-backed securities	517			2			569		17		1,086		19
	Total non-U.S. debt securities	517			2			569		17		1,086		19
	Collateralized mortgage obligations	272			3			415		5		687		8
	Total	$	3,482		$	21		$	4,197	$	80	$	7,679	$	101
		Less than 12 months						12 months or longer				Total
	December 31, 2014	Fair			Gross			Fair		Gross		Fair		Gross
		Value			Unrealized			Value		Unrealized		Value		Unrealized
	(In millions)				Losses					Losses				Losses
	Available for sale:
	U.S. Treasury and federal agencies:
	Direct obligations	$	—		$	—		$	167	$	1	$	167	$	1
	Mortgage-backed securities	2,569			9			6,466		118		9,035		127
	Asset-backed securities:
	Student loans	1,473			15			5,025		109		6,498		124
	Credit cards	344			1			1,270		33		1,614		34
	Sub-prime	—			—			896		56		896		56
	Other	547			1			791		9		1,338		10
	Total asset-backed securities	2,364			17			7,982		207		10,346		224
	Non-U.S. debt securities:
	Mortgage-backed securities	1,350			2			170		2		1,520		4
	Other	581			4			328		3		909		7
	Total non-U.S. debt securities	1,931			6			498		5		2,429		11
	State and political subdivisions	610			3			1,315		34		1,925		37
	Collateralized mortgage obligations	731			2			311		10		1,042		12
	Other U.S. debt securities	327			2			244		10		571		12
	Total	$	8,532		$	39		$	16,983	$	385	$	25,515	$	424
	Held to maturity:
	U.S. Treasury and federal agencies:
	Direct obligations	$	76		$	1		$	4,891	$	146	$	4,967	$	147
	Asset-backed securities:
	Student Loans	780			3			192		1		972		4
	Other	124			1			—		—		124		1
Total asset-backed securities	904			4			192		1		1,096		5
Non-U.S. debt securities:
Mortgage-backed securities	507			3			590		19		1,097		22
Asset-backed securities	699			1			—		—		699		1
Total non-U.S. debt securities	1,206			4			590		19		1,796		23
Collateralized mortgage obligations	422			4			547		11		969		15
Total	$	2,608		$	13		$	6,220	$	177	$	8,828	$	190
Investments Classified by Contractual Maturity Date	The following table presents contractual maturities of debt investment securities as of March 31, 2015:
	(In millions)	Under 1			1 to 5			6 to 10		Over 10
		Year			Years			Years		Years
	Available for sale:
	U.S. Treasury and federal agencies:
	Direct obligations	$	1		$	9,246		$	3,238	$	511
	Mortgage-backed securities	117			2,420			4,056		14,453
	Asset-backed securities:
	Student loans	553			5,858			3,816		1,837
	Credit cards	227			1,565			1,125		—
	Sub-prime	8			7			—		896
	Other	170			941			1,398		1,519
	Total asset-backed securities	958			8,371			6,339		4,252
	Non-U.S. debt securities:
	Mortgage-backed securities	1,661			3,511			513		2,979
	Asset-backed securities	390			2,796			112		63
	Government securities	2,236			1,575			—		—
	Other	1,340			3,152			739		—
	Total non-U.S. debt securities	5,627			11,034			1,364		3,042
	State and political subdivisions	723			2,848			4,952		2,526
	Collateralized mortgage obligations	249			1,044			1,077		3,460
	Other U.S. debt securities	1,087			2,674			277		35
	Total	$	8,762		$	37,637		$	21,303	$	28,279
	Held to maturity:
	U.S. Treasury and federal agencies:
	Direct obligations	$	—		$	—		$	4,999	$	113
	Mortgage-backed securities	—			11			11		35
	Asset-backed securities:
	Student loans	4			182			357		1,212
	Credit cards	—			375			522		—
	Other	9			370			162		4
	Total asset-backed securities	13			927			1,041		1,216
	Non-U.S. debt securities:
	Mortgage-backed securities	476			939			133		1,727
	Asset-backed securities	132			1,993			173		—
	Government securities	148			—			—		—
	Other	—			65			—		—
	Total non-U.S. debt securities	756			2,997			306		1,727
	State and political subdivisions	3			—			—		—
	Collateralized mortgage obligations	483			290			496		821
	Total	$	1,255		$	4,225		$	6,853	$	3,912
Gains and Losses Related to Investment Securities	The following tables present gross realized gains and losses from sales of available-for-sale securities, and the components of net impairment losses included in net gains and losses related to investment securities, for the periods indicated:
		Three Months Ended March 31,
	(In millions)	2015			2014
	Gross realized gains from sales of available-for-sale securities	$	—		$	15
	Gross realized losses from sales of available-for-sale securities	—			—
	Net impairment losses:
	Gross losses from other-than-temporary impairment	(1		)	(1		)
	Losses reclassified (from) to other comprehensive income, or OCI	—			(8		)
	Net impairment losses(1)	(1		)	(9		)
	Gains related to investment securities, net	$	(1	)	$	6
	(1) Net impairment losses, recognized in our consolidated statement of income, were composed of the following:
	Impairment associated with expected credit losses	$	—		$	(9	)
	Impairment associated with management's intent to sell impaired securities prior to recovery in value	—			—
	Impairment associated with adverse changes in timing of expected future cash flows	(1		)	—
	Net impairment losses	$	(1	)	$	(9	)
Schedule of Credit-Related Loss Activity Recognized in Earnings	The following table presents a roll-forward with respect to net impairment losses that have been recognized in income for the periods indicated:
		Three Months Ended March 31,
	(In millions)	2015			2014
	Balance, beginning of period	$	115		$	122
	Additions:
	Losses for which other-than-temporary impairment was not previously recognized	—			9
	Losses for which other-than-temporary impairment was previously recognized	1			—
	Reductions:
	Previously recognized losses related to securities sold or matured	(9		)	(1		)
	Losses related to securities intended or required to be sold	—			(6		)
	Balance, end of period	$	107		$	124

Loans_and_Leases_Tables

Loans and Leases (Tables)	3 Months Ended
	Mar. 31, 2015
Loans and Leases Receivable Disclosure [Abstract]
Net Loans	The following table presents our recorded investment in loans and leases, by segment and class, as of the dates indicated:
	(In millions)	March 31, 2015			December 31, 2014
	Institutional:
	Investment funds:
	U.S.	$	11,228		$	11,388
	Non-U.S.	2,232			2,333
	Commercial and financial:
	U.S.	3,294			3,061
	Non-U.S.	468			256
	Purchased receivables:
	U.S.	115			124
	Non-U.S.	4			6
	Lease financing:
	U.S.	334			335
	Non-U.S.	609			668
	Total institutional	18,284			18,171
	Commercial real estate:
	U.S.	35			28
	Total loans and leases	18,319			18,199
	Allowance for loan losses	(41		)	(38		)
	Loans and leases, net of allowance for loan losses	$	18,278		$	18,161
Recorded Investment in Each Class of Total Loans and Leases by Credit Quality Indicator	The following tables present our recorded investment in each class of loans and leases by credit quality indicator as of the dates indicated:
		Institutional										Commercial Real Estate
	March 31, 2015	Investment			Commercial and Financial			Purchased		Lease		Property Development		Other		Total
		Funds						Receivables		Financing						Loans and
	(In millions)															Leases
	Investment grade(1)	$	13,351		$	1,132		$	119	$	916	$	—	$	28	$	15,546
	Speculative(2)	109			2,630			—		27		7		—		2,773
	Total	$	13,460		$	3,762		$	119	$	943	$	7	$	28	$	18,319
		Institutional										Commercial Real Estate
	December 31, 2014	Investment			Commercial and Financial			Purchased		Lease		Property Development		Other		Total
		Funds						Receivables		Financing						Loans and
	(In millions)															Leases
	Investment grade(1)	$	13,304		$	1,011		$	130	$	976	$	—	$	—	$	15,421
	Speculative(2)	417			2,306			—		27		—		28		2,778
	Total	$	13,721		$	3,317		$	130	$	1,003	$	—	$	28	$	18,199
	(1) Investment-grade loans and leases consist of counterparties with strong credit quality and low expected credit risk and probability of default. Ratings apply to counterparties with a strong capacity to support the timely repayment of any financial commitment.
	(2) Speculative loans and leases consist of counterparties that face ongoing uncertainties or exposure to business, financial, or economic downturns. However, these counterparties may have financial flexibility or access to financial alternatives, which allow for financial commitments to be met.
Schedule of Loans and Leases Receivable by Impairment Methodology	The following table presents our recorded investment in loans and leases, disaggregated based on our impairment methodology, as of the dates indicated:
		March 31, 2015								December 31, 2014
	(In millions)	Institutional			Commercial Real Estate			Total Loans and Leases		Institutional		Commercial Real Estate		Total Loans and Leases
	Loans and leases:
	Collectively evaluated for impairment(1)	$	18,284		$	35		$	18,319	$	18,171	$	28	$	18,199
	Total	$	18,284		$	35		$	18,319	$	18,171	$	28	$	18,199
	(1) For those portfolios where there are a small number of loans each with a large balance, we review each loan annually for indicators of impairment. For those loans where no such indicators are identified, the loans are collectively evaluated for impairment. As of March 31, 2015 and December 31, 2014, all of the allowance for loan losses of $41 million and $38 million, respectively, related to institutional loans collectively evaluated for impairment.
Impaired Loans	The following table presents information related to our recorded investment in impaired loans and leases as of the dates indicated:
		March 31, 2015						December 31, 2014
	(In millions)	Recorded Investment(1)			Unpaid			Recorded Investment(1)		Unpaid
					Principal					Principal
					Balance(2)					Balance(2)
	With no related allowance recorded:
	CRE—property development—acquired credit-impaired	$	—		$	34		$	—	$	34
	CRE—other—acquired credit-impaired	—			22			—		22
	Total CRE	$	—		$	56		$	—	$	56
	(1) As of March 31, 2015 and December 31, 2014, we have no recorded investment in institutional loans.
	(2) As of March 31, 2015 and December 31, 2014, all of the allowance for loan losses of $41 million and $38 million, respectively, related to institutional loans collectively evaluated for impairment.
Schedule of Activity in the Allowance for Loan Losses	The following table presents activity in the allowance for loan losses for the periods indicated:
		Three Months Ended March 31,
		2015			2014
	(In millions)	Total Loans and Leases			Total Loans and Leases
	Allowance for loan losses(1):
	Beginning balance	$	37		$	28
	Provisions	4			2
	Ending balance	$	41		$	30
	(1) As of March 31, 2015, approximately $30 million of our allowance for loan losses was related to senior secured bank loans included in the institutional segment; the remaining $11 million was related to other commercial-and-financial loans in the institutional segment.

Goodwill_and_Other_Intangible_1

Goodwill and Other Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Changes In The Carrying Amount Of Goodwill	The following table presents changes in the carrying amount of goodwill during the periods indicated:
		Three Months Ended March 31,
		2015									2014
	(In millions)	Investment			Investment			Total			Investment			Investment			Total
		Servicing			Management						Servicing			Management
	Goodwill:
	Beginning balance	$	5,793		$	33		$	5,826		$	5,999		$	37		$	6,036
	Foreign currency translation and other, net	(160		)	(3		)	(163		)	2			—			2
	Ending balance	$	5,633		$	30		$	5,663		$	6,001		$	37		$	6,038
Changes In The Carrying Amount Of Other Intangible Assets	The following table presents changes in the net carrying amount of other intangible assets during the periods indicated:
		Three Months Ended March 31,
		2015									2014
	(In millions)	Investment			Investment			Total			Investment			Investment			Total
		Servicing			Management						Servicing			Management
	Other intangible assets:
	Beginning balance	$	1,998		$	27		$	2,025		$	2,321		$	39		$	2,360
	Amortization	(48		)	(2		)	(50		)	(52		)	(2		)	(54		)
	Foreign currency translation and other, net	(81		)	(2		)	(83		)	—			—			—
	Ending balance	$	1,869		$	23		$	1,892		$	2,269		$	37		$	2,306
Schedule of Finite-Lived Intangible Assets	The following table presents the gross carrying amount, accumulated amortization and net carrying amount of other intangible assets by type as of the dates indicated:
		March 31, 2015									December 31, 2014
	(In millions)	Gross			Accumulated			Net			Gross			Accumulated			Net
		Carrying			Amortization			Carrying			Carrying			Amortization			Carrying
		Amount						Amount			Amount						Amount
	Client relationships	$	2,471		$	(1,087	)	$	1,384		$	2,569		$	(1,088	)	$	1,481
	Core deposits	664			(220		)	444			688			(219		)	469
	Other	170			(106		)	64			214			(139		)	75
	Total	$	3,305		$	(1,413	)	$	1,892		$	3,471		$	(1,446	)	$	2,025

Other_Assets_Tables

Other Assets (Tables)	3 Months Ended
	Mar. 31, 2015
Other Assets [Abstract]
Components of Other Assets	The following table presents the components of other assets as of the dates indicated:
	(In millions)	March 31, 2015		December 31, 2014
	Collateral deposits, net	$	22,094	$	18,134
	Unrealized gains on derivative financial instruments, net	8,048		7,934
	Bank-owned life insurance	2,419		2,402
	Investments in joint ventures and other unconsolidated entities	1,875		1,798
	Accounts receivable	1,087		513
	Receivable for securities settlement	419		218
	Prepaid expenses	376		259
	Income taxes receivable	295		396
	Deferred tax assets, net of valuation allowance	189		214
	Deposits with clearing organizations	181		197
	Receivable for securities sold	45		—
	Other(1)	521		535
	Total	$	37,549	$	32,600
	(1)	Includes other real estate owned of approximately $63 million and $62 million as of March 31, 2015 and December 31, 2014, respectively.

Commitments_and_Guarantees_Tab

Commitments and Guarantees (Tables)	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Schedule of Guarantor Obligations	The following table, which presents the aggregate gross contractual amounts of our off-balance sheet guarantees as of the dates indicated, does not consider the value of any collateral, which may mitigate any potential loss. Amounts presented do not reflect participations to independent third parties.
	(In millions)	March 31, 2015		December 31, 2014
	Indemnified securities financing	$	348,960	$	349,766
	Stable value protection	23,425		23,409
	Asset purchase agreements	4,212		4,107
	Standby letters of credit	4,782		4,720
Schedule of Repurchase Agreements	The following table summarizes the aggregate fair values of indemnified securities financing and related collateral, as well as collateral invested in indemnified repurchase agreements, as of the dates indicated:
	(In millions)	March 31, 2015		December 31, 2014
	Fair value of indemnified securities financing	$	348,960	$	349,766
	Fair value of cash and securities held by us, as agent, as collateral for indemnified securities financing	364,212		364,411
	Fair value of collateral for indemnified securities financing invested in indemnified repurchase agreements	78,163		85,309
	Fair value of cash and securities held by us or our agents as collateral for investments in indemnified repurchase agreements	83,256		90,819

Contingencies_Tables

Contingencies (Tables)	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Schedule of Total Worldwide Revenue from Foreign Exchanges	The following table summarizes our estimated total revenue worldwide from indirect foreign exchange trading for the periods indicated:
	(In millions)	Revenue from indirect foreign exchange trading
	Twelve Months Ended December 31, 2008	$	462
	Twelve Months Ended December 31, 2009	369
	Twelve Months Ended December 31, 2010	336
	Twelve Months Ended December 31, 2011	331
	Twelve Months Ended December 31, 2012	248
	Twelve Months Ended December 31, 2013	285
	Twelve Months Ended December 31, 2014	246
	Three Months Ended March 31, 2015	68

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Income (Tables)	3 Months Ended
	Mar. 31, 2015
Stockholders' Equity Note [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	The following table presents the after-tax components of AOCI as of the dates indicated:
	(In millions)	March 31, 2015			December 31, 2014
	Net unrealized gains on cash flow hedges	$	288		$	276
	Net unrealized gains (losses) on available-for-sale securities portfolio	472			273
	Net unrealized gains (losses) related to reclassified available-for-sale securities	35			39
	Net unrealized gains (losses) on available-for-sale securities	507			312
	Net unrealized losses on available-for-sale securities designated in fair value hedges	(136		)	(121		)
	Other-than-temporary impairment on available-for-sale securities related to factors other than credit	—			1
	Net unrealized losses on hedges of net investments in non-U.S. subsidiaries	(14		)	(14		)
	Other-than-temporary impairment on held-to-maturity securities related to factors other than credit	(25		)	(29		)
	Net unrealized losses on retirement plans	(267		)	(272		)
	Foreign currency translation	(1,359		)	(660		)
	Total	$	(1,006	)	$	(507	)
	The following tables present changes in AOCI by component, net of related taxes, for the periods indicated:
		Three Months Ended March 31, 2015
	(In millions)	Net Unrealized Gains (Losses) on Cash Flow Hedges			Net Unrealized Gains (Losses) on Available-for-Sale Securities			Net Unrealized Losses on Hedges of Net Investments in Non-U.S. Subsidiaries			Other-Than-Temporary Impairment on Held-to-Maturity Securities			Net Unrealized Losses on Retirement Plans			Foreign Currency Translation			Total
	Balance as of December 31, 2014	$	276		$	192		$	(14	)	$	(29	)	$	(272	)	$	(660	)	$	(507	)
	Other comprehensive income (loss) before reclassifications	11			179			—			5			—			(699		)	(504		)
	Amounts reclassified into earnings	1			—			—			(1		)	5			—			5
	Other comprehensive income (loss)	12			179			—			4			5			(699		)	(499		)
	Balance as of March 31, 2015	$	288		$	371		$	(14	)	$	(25	)	$	(267	)	$	(1,359	)	$	(1,006	)
		Three Months Ended March 31, 2014
	(In millions)	Net Unrealized Gains (Losses) on Cash Flow Hedges			Net Unrealized Gains (Losses) on Available-for-Sale Securities			Net Unrealized Losses on Hedges of Net Investments in Non-U.S. Subsidiaries			Other-Than-Temporary Impairment on Held-to-Maturity Securities			Net Unrealized Losses on Retirement Plans			Foreign Currency Translation			Total
	Balance as of December 31, 2013	$	161		$	(221	)	$	(14	)	$	(47	)	$	(203	)	$	229		$	(95	)
	Other comprehensive income (loss) before reclassifications	(8		)	258			—			8			1			27			286
	Amounts reclassified into earnings	1			(9		)	—			—			5			—			(3		)
	Other comprehensive income (loss)	(7		)	249			—			8			6			27			283
	Balance as of March 31, 2014	$	154		$	28		$	(14	)	$	(39	)	$	(197	)	$	256		$	188
Schedule of Reclassifications Out of AOCI	The following table presents after-tax reclassifications into earnings for the periods indicated:
		Three Months Ended March 31,
		2015			2014
	(In millions)	Amounts Reclassified into Earnings						Affected Line Item in Consolidated Statement of Income
	Cash flow hedges:
	Interest-rate contracts	$	1		$	1		Net interest revenue
	Available-for-sale securities:
	Net realized gains from sales of available-for-sale securities, net of related taxes of ($6)	—			(9		)	Net gains (losses) from sales of available-for-sale securities
	Held-to-maturity securities:
	Other-than-temporary impairment on held-to-maturity securities related to factors other than credit	(1		)	—			Losses reclassified (from) to other comprehensive income
	Retirement plans:
	Amortization of actuarial losses, net of related taxes of ($4) and tax benefits of $3, respectively	5			5			Compensation and employee benefits expenses
	Total reclassifications out of AOCI	$	5		$	(3	)

Regulatory_Capital_Tables

Regulatory Capital (Tables)	3 Months Ended
	Mar. 31, 2015
Banking and Thrift [Abstract]
Schedule of Regulatory Capital	The following table presents the regulatory capital structure, total risk-weighted assets, related regulatory capital ratios and the minimum required regulatory capital ratios for State Street and State Street Bank as of the dates indicated. As a result of changes in the methodologies used to calculate our regulatory capital ratios from period to period as the provisions of the Basel III final rule are phased in, the ratios presented in the table for each period-end are not directly comparable. Refer to the footnotes following the table.
						State Street												State Street Bank
	(Dollars in millions)					Basel III Advanced Approaches March 31, 2015(1)			Basel III Standardized Approach March 31, 2015(2)			Basel III Advanced Approaches December 31, 2014(1)			Basel III Transitional Approach December 31, 2014(3)			Basel III Advanced Approaches March 31, 2015(1)			Basel III Standardized Approach March 31, 2015(2)			Basel III Advanced Approaches December 31, 2014(1)			Basel III Transitional Approach December 31, 2014(3)
	Common shareholders' equity:
	Common stock and related surplus					$	10,248		$	10,248		$	10,295		$	10,295		$	10,901		$	10,901		$	10,867		$	10,867
	Retained earnings					15,135			15,135			14,882			14,882			9,801			9,801			9,416			9,416
	Accumulated other comprehensive income (loss)					(1,226		)	(1,226		)	(641		)	(641		)	(1,048		)	(1,048		)	(535		)	(535		)
	Treasury stock, at cost					(5,519		)	(5,519		)	(5,158		)	(5,158		)	—			—			—			—
	Total					18,638			18,638			19,378			19,378			19,654			19,654			19,748			19,748
	Regulatory capital adjustments:
	Goodwill and other intangible assets, net of associated deferred tax liabilities(4)					(5,932		)	(5,932		)	(5,869		)	(5,869		)	(5,632		)	(5,632		)	(5,577		)	(5,577		)
	Other adjustments					(62		)	(62		)	(36		)	(36		)	(102		)	(102		)	(128		)	(128		)
	Common equity tier 1 capital					12,644			12,644			13,473			13,473			13,920			13,920			14,043			14,043
	Preferred stock					1,961			1,961			1,961			1,961			—			—			—			—
	Trust preferred capital securities subject to phase-out from tier 1 capital					237			237			475			475			—			—			—			—
	Other adjustments					(94		)	(94		)	(145		)	(145		)	—			—			—			—
	Tier 1 capital					14,748			14,748			15,764			15,764			13,920			13,920			14,043			14,043
	Qualifying subordinated long-term debt					1,439			1,439			1,618			1,618			1,453			1,453			1,634			1,634
	Trust preferred capital securities phased out of tier 1 capital					713			713			475			475			—			—			—			—
	Other adjustments					2			2			4			4			—			—			—			—
	Total capital					$	16,902		$	16,902		$	17,861		$	17,861		$	15,373		$	15,373		$	15,677		$	15,677
	Risk-weighted assets:
	Credit risk					$	63,820		$	119,582		$	66,874		$	87,502		$	56,527		$	112,454		$	59,836		$	84,433
	Operational risk					35,765			NA			35,866			NA			35,348			NA			35,449			NA
	Market risk(5)					4,413			2,364			5,087			2,910			4,407			2,363			5,048			2,909
	Total risk-weighted assets					$	103,998		$	121,946		$	107,827		$	90,412		$	96,282		$	114,817		$	100,333		$	87,342
	Adjusted quarterly average assets					$	252,406		$	252,406		$	247,740		$	247,740		$	248,022		$	248,022		$	243,549		$	243,549
	Capital Ratios:	Minimum Requirements(6) 2015		Minimum Requirements(7) 2014
	Common equity tier 1 capital	4.5	%	4	%	12.2		%	10.4		%	12.5		%	14.9		%	14.5		%	12.1		%	14		%	16.1		%
	Tier 1 capital	6		5.5		14.2			12.1			14.6			17.4			14.5			12.1			14			16.1
	Total capital	8		8		16.3			13.9			16.6			19.8			16			13.4			15.6			17.9
	Tier 1 leverage	4		4		5.8			5.8			6.4			6.4			5.6			5.6			5.8			5.8
	NA: Not applicable.
	(1) Common equity tier 1 capital, tier 1 capital and total capital ratios as of March 31, 2015 and December 31, 2014 were calculated in conformity with the advanced approaches provisions of the Basel III final rule. Tier 1 leverage ratio as of March 31, 2015 and December 31, 2014 were calculated in conformity with the Basel III final rule.
	(2) Common equity tier 1 capital, tier 1 capital and total capital ratios as of March 31, 2015 were calculated in conformity with the standardized approach provisions of the Basel III final rule. Tier 1 leverage ratio as of March 31, 2015 was calculated in conformity with the Basel III final rule.
	(3) Common equity tier 1 capital, tier 1 capital, total capital and tier 1 leverage ratios as of December 31, 2014 were calculated in conformity with the transitional provisions of the Basel III final rule. Specifically, these ratios reflect common equity tier 1, tier 1 and total capital (the numerator) calculated in conformity with the provisions of the Basel III final rule, and total risk-weighted assets or, with respect to the tier 1 leverage ratio, quarterly average assets (in both cases, the denominator), calculated in conformity with the provisions of Basel I.
	(4) Amounts for State Street and State Street Bank as of March 31, 2015 consisted of goodwill, net of associated deferred tax liabilities, and 40% of other intangible assets, net of associated deferred tax liabilities. Amounts for State Street and State Street Bank as of December 31, 2014 consisted of goodwill, net of deferred tax liabilities and 20% of other intangible assets, net of associated deferred tax liabilities. Intangible assets, net of associated deferred tax liabilities is phased in as a deduction from capital, in conformity with the Basel III final rule.
	(5) Market risk risk-weighted assets reported in conformity with the Basel III advanced approaches included a credit valuation adjustment, or CVA, which reflected the risk of potential fair-value adjustments for credit risk reflected in our valuation of over-the-counter derivative contracts.  The CVA was not provided for in the final market risk capital rule; however, it was required by the advanced approaches provisions of the Basel III final rule.  State Street used the simple CVA approach in conformity with the Basel III advanced approaches.
	(6) Minimum requirements will be phased in up to full implementation beginning on January 1, 2019; minimum requirements listed are as of March 31, 2015.
	(7) Minimum requirements will be phased in up to full implementation beginning on January 1, 2019; minimum requirements listed are as of December 31, 2014.

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Outstanding Hedges: (Notional Amount)	The following table presents the aggregate contractual, or notional, amounts of derivative financial instruments entered into in connection with our trading and asset-and-liability management activities as of the dates indicated:
	(In millions)	March 31,				December 31,
		2015				2014
	Derivatives not designated as hedging instruments:
	Interest-rate contracts:
	Swap agreements and forwards	$	474			$	645
	Options and caps purchased	4				7
	Options and caps written	4				7
	Futures	2,969				3,939
	Foreign exchange contracts:
	Forward, swap and spot	1,414,506				1,231,344
	Options purchased	3,008				2,767
	Options written	2,905				2,404
	Futures	21				—
	Credit derivative contracts:
	Credit swap agreements	226				191
	Commodity and equity contracts:
	Commodity(1)	61				26
	Equity(1)	92				2
	Other:
	Stable value contracts	23,425				23,409
	Deferred value awards(2)	417				210
	Derivatives designated as hedging instruments:
	Interest-rate contracts:
	Swap agreements	6,065				6,077
	Foreign exchange contracts:
	Forward and swap	2,605				2,705
	(1) Primarily composed of positions held by a consolidated sponsored investment fund, more fully described in note 9.
	(2) Represents grants of deferred value awards to employees; refer to discussion in this note under "Derivatives Not Designated as Hedging Instruments."
Notional Amount of Interest Rate Swap Agreements Designated as Fair Value and Cash Flow Hedges	The following table presents the aggregate notional amounts of these interest-rate contracts and the related assets or liabilities being hedged as of the dates indicated:
		March 31, 2015(1)
	(In millions)	Fair
		Value
		Hedges
	Investment securities available for sale	$	2,565
	Long-term debt(2)	3,500
	Total	$	6,065
		December 31, 2014
	(In millions)	Fair
		Value
		Hedges
	Investment securities available for sale	$	2,577
	Long-term debt(2)	3,500
	Total	$	6,077
	(1) As of March 31, 2015 there were no interest-rate contracts designated as cash flow hedges.
	(2) As of March 31, 2015, these fair value hedges increased the carrying value of long-term debt presented in our consolidated statement of condition by $135 million. As of December 31, 2014, these fair value hedges decreased the carrying value of long-term debt presented in our consolidated statement of condition by $76 million.
Contractual and Weighted-Average Interest Rates, Which Include the Effects of Hedges Related to Financial Instruments	The following tables present the contractual and weighted-average interest rates for long-term debt, which include the effects of the fair value hedges presented in the table above, for the periods indicated:
		Three Months Ended March 31,
		2015						2014
		Contractual			Rate			Contractual			Rate
		Rates			Including			Rates			Including
					Impact of Hedges						Impact of Hedges
	Long-term debt	3.53	%		2.54	%		3.39	%		2.6	%
Schedule of the Fair Values of Derivative Financial Instruments	The following tables present the fair value of derivative financial instruments, excluding the impact of master netting agreements, recorded in our consolidated statement of condition as of the dates indicated. The impact of master netting agreements is disclosed in note 2.
	Derivative Assets(1)
		Fair Value
	(In millions)	March 31, 2015				December 31, 2014
	Derivatives not designated as hedging instruments:
	Foreign exchange contracts	$	15,610			$	14,626
	Interest-rate contracts	12				15
	Other derivative contracts	3				2
	Total	$	15,625			$	14,643
	Derivatives designated as hedging instruments:
	Foreign exchange contracts	$	506			$	509
	Interest-rate contracts	129				62
	Total	$	635			$	571
	(1) Derivative assets are included within other assets in our consolidated statement of condition.
	Derivative Liabilities(1)
		Fair Value
	(In millions)	March 31, 2015				December 31, 2014
	Derivatives not designated as hedging instruments:
	Foreign exchange contracts	$	17,053			$	14,922
	Other derivative contracts	112				70
	Interest-rate contracts	12				16
	Total	$	17,177			$	15,008
	Derivatives designated as hedging instruments:
	Interest-rate contracts	$	220			$	223
	Foreign exchange contracts	—				3
	Total	$	220			$	226
	(1) Derivative liabilities are included within other liabilities in our consolidated statement of condition.
Impact of Derivatives on Consolidated Statement of Income	The following tables present the impact of our use of derivative financial instruments on our consolidated statement of income for the periods indicated:
		Location of Gain (Loss) on		Amount of Gain (Loss) on Derivative Recognized
		Derivative in Consolidated		in Consolidated Statement of Income
		Statement of Income
				Three Months Ended March 31,
	(In millions)			2015				2014
	Derivatives not designated as hedging instruments:
	Foreign exchange contracts	Trading services revenue		$	204			$	134
	Interest-rate contracts	Processing fees and other revenue		1				—
	Other derivative contracts	Trading services revenue		2				(1		)
	Total			$	207			$	133
		Location of (Gain) Loss on		Amount of (Gain) Loss on Derivative Recognized
		Derivative in Consolidated		in Consolidated Statement of Income
		Statement of Income
				Three Months Ended March 31,
	(In millions)			2015				2014
	Derivatives not designated as hedging instruments:
	Other derivative contracts	Compensation and employee benefits		$	59			$	49
	Total			$	59			$	49
Schedule of Differences Between the Gains (Losses) on the Derivative and the Gains (Losses) on the Hedged Item
		Location of Gain (Loss) on Derivative in Consolidated Statement of Income		Amount of Gain								Hedged Item in Fair Value Hedging Relationship		Location of Gain (Loss) on Hedged Item in Consolidated Statement of Income	Amount of Gain
				(Loss) on Derivative											(Loss) on Hedged
				Recognized in											Item Recognized in
				Consolidated											Consolidated
				Statement of Income											Statement of Income
				Three Months Ended March 31,											Three Months Ended March 31,
	(In millions)			2015				2014							2015			2014
	Derivatives designated as fair value hedges:
	Foreign exchange contracts	Processing fees and		$	(67	)		42				Investment securities		Processing fees and	$	67		$	(42	)
		other revenue												other revenue
	Interest-rate contracts	Processing fees and		(25		)		(12		)		Available-for-sale securities		Processing fees and	25			12
		other revenue												other revenue(1)
	Interest-rate contracts	Processing fees and		68				49				Long-term debt		Processing fees and	(65		)	(45		)
		other revenue												other revenue
	Total			$	(24	)		$	79						$	27		$	(75	)
	(1) Represents amounts reclassified out of or into other comprehensive income, or OCI. For the three months ended March 31, 2015, $15 million of unrealized losses on available-for-sale securities designated in fair value hedges were recognized in OCI. For the three months ended March 31, 2014, $10 million of unrealized gains on available-for-sale securities designated in fair value hedges were recognized in OCI.
	Differences between the gains (losses) on the derivative and the gains (losses) on the hedged item, excluding any amounts recorded in net interest revenue, represent hedge ineffectiveness.
		Amount of Gain								Location of Gain (Loss) Reclassified from OCI to Consolidated Statement of Income		Amount of Gain						Location of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income		Amount of Gain
		(Loss) on Derivative										(Loss) Reclassified								(Loss) on Derivative
		Recognized in Other										from OCI to								Recognized in
		Comprehensive										Consolidated								Consolidated
		Income										Statement of Income								Statement of Income
		Three Months Ended March 31,										Three Months Ended March 31,								Three Months Ended March 31,
		2015				2014						2015			2014					2015		2014
	(In millions)
	Derivatives designated as cash flow hedges:
	Interest-rate contracts	$	—			$	(1	)		Net interest revenue		$	(1	)	$	(1	)	Net interest revenue		$	—	$	1
	Foreign exchange contracts	20				(12		)		Net interest revenue		—			—			Net interest revenue		2		1
	Total	$	20			$	(13	)				$	(1	)	$	(1	)			$	2	$	2

Offsetting_Arrangements_Tables

Offsetting Arrangements (Tables)	3 Months Ended
	Mar. 31, 2015
Offsetting [Abstract]
Offsetting Assets	The following tables present information about the offsetting of assets related to derivative contracts and secured financing transactions, as of the dates indicated:
	Assets:	31-Mar-15								31-Dec-14
	(In millions)	Gross Amounts of Recognized Assets(1)		Gross Amounts Offset in Statement of Condition(2)			Net Amounts of Assets Presented in Statement of Condition			Gross Amounts of Recognized Assets(1)		Gross Amounts Offset in Statement of Condition(2)			Net Amounts of Assets Presented in Statement of Condition
	Derivatives:
	Foreign exchange contracts	$	16,116	$	(7,730	)	$	8,386		$	15,135	$	(6,275	)	$	8,860
	Interest-rate contracts	141		(14		)	127			77		(21		)	56
	Other derivative contracts	3		(2		)	1			2		(1		)	1
	Cash collateral netting	—		(466		)	(466		)	—		(983		)	(983		)
	Total derivatives	$	16,260	$	(8,212	)	$	8,048		$	15,214	$	(7,280	)	$	7,934
	Other financial instruments:
	Resale agreements and securities borrowing(3)	$	62,587	$	(31,407	)	$	31,180		$	47,488	$	(29,157	)	$	18,331
	Total derivatives and other financial instruments	$	78,847	$	(39,619	)	$	39,228		$	62,702	$	(36,437	)	$	26,265
	(1) Amounts include all transactions regardless of whether or not they are subject to an enforceable netting arrangement.
	(2) Amounts subject to netting arrangements which have been determined to be legally enforceable.
	(3) Included in the $31,180 million as of March 31, 2015 were $11,331 million of resale agreements and $19,849 million of collateral provided related to securities borrowing. Included in the $18,331 million as of December 31, 2014 were $2,390 million of resale agreements and $15,941 million of collateral provided related to securities borrowing. Resale agreements and collateral provided related to securities borrowing were recorded in securities purchased under resale agreements and other assets, respectively, in our consolidated statement of condition. Refer to note 7 for additional information with respect to principal securities finance transactions.
		31-Mar-15										31-Dec-14
				Gross Amounts Not Offset in Statement of Condition(1)											Gross Amounts Not Offset in Statement of Condition(1)
	(In millions)	Net Amount of Assets Presented in Statement of Condition		Counterparty Netting			Collateral Received			Net Amount(2)		Net Amount of Assets Presented in Statement of Condition			Counterparty Netting			Collateral Received			Net Amount(2)
	Derivatives	$	8,048	$	—		$	(1,442	)	$	6,606	$	7,934		$	—		$	(1,490	)	$	6,444
	Resale agreements and securities borrowing	31,180		(283		)	(30,842		)	55		18,331			(128		)	(18,157		)	46
	Total	$	39,228	$	(283	)	$	(32,284	)	$	6,661	$	26,265		$	(128	)	$	(19,647	)	$	6,490
	(1) Amounts subject to netting arrangements which have been determined to be legally enforceable.
	(2) Includes amounts secured by collateral not determined to be subject to enforceable netting arrangements.
Offsetting Liabilities	The following tables present information about the offsetting of liabilities related to derivative contracts and secured financing transactions, as of the dates indicated:
	Liabilities:	31-Mar-15								31-Dec-14
	(In millions)	Gross Amounts of Recognized Liabilities(1)		Gross Amounts Offset in Statement of Condition(2)			Net Amounts of Liabilities Presented in Statement of Condition			Gross Amounts of Recognized Liabilities(1)		Gross Amounts Offset in Statement of Condition(2)			Net Amounts of Liabilities Presented in Statement of Condition
	Derivatives:
	Foreign exchange contracts	$	17,053	$	(7,730	)	$	9,323		$	14,925	$	(6,275	)	$	8,650
	Interest-rate contracts	232		(14		)	218			239		(20		)	219
	Other derivative contracts	112		(2		)	110			70		(1		)	69
	Cash collateral netting	—		(2,661		)	(2,661		)	—		(2,630		)	(2,630		)
	Total derivatives	$	17,397	$	(10,407	)	$	6,990		$	15,234	$	(8,926	)	$	6,308
	Other financial instruments:
	Repurchase agreements and securities lending(3)	$	48,718	$	(31,407	)	$	17,311		$	44,562	$	(29,157	)	$	15,405
	Total derivatives and other financial instruments	$	66,115	$	(41,814	)	$	24,301		$	59,796	$	(38,083	)	$	21,713
	(1) Amounts include all transactions regardless of whether or not they are subject to an enforceable netting arrangement.
	(2) Amounts subject to netting arrangements which have been determined to be legally enforceable.
	(3) Included in the $17,311 million as of March 31, 2015 were $10,158 million of repurchase agreements and $7,153 million of collateral received related to securities lending. Included in the $15,405 million as of December 31, 2014 were $8,925 million of repurchase agreements and $6,480 million of collateral received related to securities lending. Repurchase agreements and collateral received related to securities lending were recorded in securities sold under repurchase agreements and accrued expenses and other liabilities, respectively, in our consolidated statement of condition. Refer to note 7 for additional information with respect to principal securities finance transactions.
		31-Mar-15										31-Dec-14
				Gross Amounts Not Offset in Statement of Condition(1)											Gross Amounts Not Offset in Statement of Condition(1)
	(In millions)	Net Amount of Liabilities Presented in Statement of Condition		Counterparty Netting			Collateral Provided			Net Amount(2)		Net Amount of Liabilities Presented in Statement of Condition			Counterparty Netting			Collateral Provided			Net Amount(2)
	Derivatives	$	6,990	$	—		$	(110	)	$	6,880	$	6,308		$	—		$	(19	)	$	6,289
	Repurchase agreements and securities lending	17,311		(283		)	(15,274		)	1,754		15,405			(128		)	(13,872		)	1,405
	Total	$	24,301	$	(283	)	$	(15,384	)	$	8,634	$	21,713		$	(128	)	$	(13,891	)	$	7,694
	(1) Amounts subject to netting arrangements which have been determined to be legally enforceable.
	(2) Includes amounts secured by collateral not determined to be subject to enforceable netting arrangements.

Net_Interest_Revenue_Tables

Net Interest Revenue (Tables)	3 Months Ended
	Mar. 31, 2015
Net Interest Revenue [Abstract]
Components of Interest Revenue and Interest Expense	The following table presents the components of interest revenue and interest expense, and related net interest revenue, for the periods indicated:
		Three Months Ended March 31,
	(In millions)	2015		2014
	Interest revenue:
	Deposits with banks	$	54	$	34
	Investment securities:
	U.S. Treasury and federal agencies	183		163
	State and political subdivisions	58		71
	Other investments	259		319
	Securities purchased under resale agreements	11		9
	Loans and leases	74		58
	Other interest-earning assets	3		1
	Total interest revenue	642		655
	Interest expense:
	Deposits	26		15
	Short-term borrowings	1		15
	Long-term debt	62		63
	Other interest-bearing liabilities	7		7
	Total interest expense	96		100
	Net interest revenue	$	546	$	555

Expenses_Tables

Expenses (Tables)	3 Months Ended
	Mar. 31, 2015
Other Expenses [Abstract]
Schedule of Acquisition and Restructuring Costs	The following table presents aggregate activity associated with accruals that resulted from the charges associated with the recently completed Business Operations and Information Technology Transformation program:
	(In millions)	Employee-			Real Estate Consolidation			Asset and Other Write-Offs			Total
		Related
		Costs
	Balance as of December 31, 2014	$	40		$	24		$	7		$	71
	Additional accruals for Business Operations and Information Technology Transformation program	(3		)	—			—			(3		)
	Additional accruals for 2012 expense control measures	—			—			4			4
	Payments and adjustments	(10		)	(3		)	(5		)	(18		)
	Balance as of March 31, 2015	$	27		$	21		$	6		$	54
	The following table presents net acquisition and restructuring costs recorded in the periods indicated:
		Three Months Ended March 31,
	(In millions)	2015			2014
	Acquisition costs	$	5		$	21
	Restructuring charges, net	1			12
	Total acquisition and restructuring costs	$	6		$	33

Earnings_Per_Common_Share_Tabl

Earnings Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Computation of Basic and Diluted Earnings Per Share	The following tables present the computation of basic and diluted earnings per common share for the periods indicated:
		Three Months Ended March 31,
	(Dollars in millions, except per share amounts)	2015			2014
	Net income	$	409		$	363
	Less:
	Preferred stock dividends	(31		)	(6		)
	Dividends and undistributed earnings allocated to participating securities(1)	(1		)	(1		)
	Net income available to common shareholders	$	377		$	356
	Average common shares outstanding (in thousands):
	Basic average common shares	412,225			430,621
	Effect of dilutive securities: common stock options and common stock awards	6,525			8,194
	Diluted average common shares	418,750			438,815
	Anti-dilutive securities(2)	791			1,504
	Earnings per Common Share:
	Basic	$	0.91		$	0.83
	Diluted(3)	0.9			0.81
	(1) Represents the portion of net income available to common equity allocated to participating securities, composed of fully vested deferred director stock and unvested restricted stock that contain non-forfeitable rights to dividends during the vesting period on a basis equivalent to dividends paid to common shareholders.
	(2) Represents common stock options and other equity-based awards outstanding but not included in the computation of diluted average common shares, because their effect was anti-dilutive.
	(3) Calculations reflect allocation of earnings to participating securities using the two-class method, as this computation is more dilutive than the treasury stock method.

Line_of_Business_Information_T

Line of Business Information (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Summary of Line of Business Results	The following is a summary of our line-of-business results for the periods indicated. The “Other” column represents costs incurred that are not allocated to a specific line of business, including certain severance and restructuring costs, acquisition costs and certain provisions for legal contingencies.
		Three Months Ended March 31,
		Investment						Investment						Other						Total
		Servicing						Management
		2015			2014			2015			2014			2015			2014			2015			2014
	(Dollars in millions,
	except where otherwise noted)
	Servicing fees	$	1,273		$	1,238		$	—		$	—		$	—		$	—		$	1,273		$	1,238
	Management fees	—			—			301			292			—			—			301			292
	Trading services	315			241			9			12			—			—			324			253
	Securities finance	101			85			—			—			—			—			101			85
	Processing fees and other	59			55			2			1			—			—			61			56
	Total fee revenue	1,748			1,619			312			305			—			—			2,060			1,924
	Net interest revenue	545			551			1			4			—			—			546			555
	Gains (losses) related to investment securities, net	(1		)	6			—			—			—			—			(1		)	6
	Total revenue	2,292			2,176			313			309			—			—			2,605			2,485
	Provision for loan losses	4			2			—			—			—			—			4			2
	Total expenses	1,836			1,672			256			245			5			111			2,097			2,028
	Income before income tax expense	$	452		$	502		$	57		$	64		$	(5	)	$	(111	)	$	504		$	455
	Pre-tax margin	20		%	23		%	18		%	21		%							19		%	18		%

NonUS_Activities_Tables

Non-U.S. Activities (Tables)	3 Months Ended
	Mar. 31, 2015
Segments, Geographical Areas [Abstract]
Schedule of Results from Non-U.S. Operations	The following table presents our non-U.S. financial results for the periods indicated.
		Three Months Ended March 31,
	(In millions)	2015			2014
	Total fee revenue	$	857		$	788
	Net interest revenue	291			312
	Gains (losses) related to investment securities, net	(1		)	6
	Total revenue	1,147			1,106
	Expenses	805			852
	Income before income taxes	342			254
	Income tax expense	78			61
	Net income	$	264		$	193
Summary of Non-U.S. Assets	The following table presents the significant components of our non-U.S. assets as of the dates indicated, based on the domicile of the underlying counterparties:
	(In millions)	March 31, 2015			December 31, 2014
	Interest-bearing deposits with banks	$	26,893		$	17,382
	Investment securities	26,863			29,060
	Other assets	13,948			13,577
	Total non-U.S. assets	$	67,704		$	60,019

Basis_of_Presentation_Narrativ

Basis of Presentation Narrative (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Accounting Policies [Abstract]
Debt Issuance Cost	$28

Fair_Value_Narrative_Details

Fair Value - Narrative (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Assets, level 1 to level 2 transfers	$0		$0
Assets, level 2 to level 1 transfers	0		0
Liabilities, level 1 to level 2 transfers	0		0
Liabilities, level 2 to level 1 transfers	0		0
Transfers Into Level 3	0	0
Transfers out of Level 3	$0	$0

Fair_Value_Schedule_of_Fair_Va

Fair Value - Schedule of Fair Value Measurements on a Recurring Basis (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	$1,145,000,000		$924,000,000
Investment securities available for sale	96,612,000,000		94,913,000,000
Reduction in assets from netting and the result of cash collateral deposited with derivative counterparties	466,000,000	983,000,000
Reduction in liabilities from netting and the result of cash collateral received from derivative counterparties	2,660,000,000	2,630,000,000
Pricing Methods with Significant Unobservable Market Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value disclosure	5,356,000,000		5,447,000,000
Total liabilities carried at fair value	181,000,000		83,000,000
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	1,145,000,000		924,000,000
Investment securities available for sale	96,612,000,000		94,913,000,000
Derivative Asset, Gross Liability and Obligation to Return Cash, Offset	-8,212,000,000		-7,280,000,000
Derivative assets	8,048,000,000		7,934,000,000
Assets, fair value disclosure	105,805,000,000		103,771,000,000
Derivative Liability, Gross Asset and Right to Reclaim Cash, Offset	-10,407,000,000		-8,926,000,000
Derivative liabilities	6,990,000,000		6,308,000,000
Total liabilities carried at fair value	6,994,000,000		6,308,000,000
Recurring | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Gross Liability and Obligation to Return Cash, Offset	-8,087,000,000		-7,211,000,000
Derivative assets	8,029,000,000		7,924,000,000
Derivative Liability, Gross Asset and Right to Reclaim Cash, Offset	-10,361,000,000		-8,879,000,000
Derivative liabilities	6,692,000,000		6,046,000,000
Recurring | Interest-rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Gross Liability and Obligation to Return Cash, Offset	-123,000,000		-68,000,000
Derivative assets	18,000,000		9,000,000
Derivative Liability, Gross Asset and Right to Reclaim Cash, Offset	-44,000,000		-46,000,000
Derivative liabilities	188,000,000		193,000,000
Recurring | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Gross Liability and Obligation to Return Cash, Offset	-2,000,000		-1,000,000
Derivative assets	1,000,000		1,000,000
Derivative Liability, Gross Asset and Right to Reclaim Cash, Offset	-2,000,000		-1,000,000
Derivative liabilities	110,000,000		69,000,000
Recurring | U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	20,000,000		20,000,000
Recurring | Non-U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	569,000,000		378,000,000
Recurring | Other U.S. debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	556,000,000		526,000,000
Investment securities available for sale	4,073,000,000		4,109,000,000
Trading liabilities	4,000,000
Recurring | US Treasury and federal agencies, direct obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	12,996,000,000		10,655,000,000
Recurring | US Treasury and federal agencies, mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	21,046,000,000		20,714,000,000
Recurring | Total asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	19,920,000,000		20,609,000,000
Recurring | Asset-backed securities, student loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	12,064,000,000		12,460,000,000
Recurring | Asset-backed securities, credit cards
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	2,917,000,000		3,053,000,000
Recurring | Asset-backed securities, sub-prime
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	911,000,000		951,000,000
Recurring | Asset-backed securities, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	4,028,000,000		4,145,000,000
Recurring | Total non-U.S. debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	21,067,000,000		22,169,000,000
Recurring | Non-U.S. debt securities, mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	8,664,000,000		9,606,000,000
Recurring | Non-U.S. debt securities, asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	3,361,000,000		3,226,000,000
Recurring | Government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	3,811,000,000		3,909,000,000
Recurring | Non-U.S. debt securities, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	5,231,000,000		5,428,000,000
Recurring | State and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	11,049,000,000		10,820,000,000
Recurring | Collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	5,830,000,000		5,339,000,000
Recurring | U.S. equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	39,000,000		39,000,000
Recurring | Non-U.S. equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	2,000,000		2,000,000
Recurring | U.S. money-market mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	582,000,000		449,000,000
Recurring | Non-U.S. money-market mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	8,000,000		8,000,000
Recurring | Quoted Market Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	609,000,000		418,000,000
Investment securities available for sale	12,418,000,000		10,056,000,000
Derivative Asset, Gross Asset	0		0
Assets, fair value disclosure	13,027,000,000		10,474,000,000
Derivative Liability, Gross Liability	0		0
Total liabilities carried at fair value	4,000,000		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Gross Asset	0		0
Derivative Liability, Gross Liability	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | Interest-rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Gross Asset	0		0
Derivative Liability, Gross Liability	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Gross Asset	0		0
Derivative Liability, Gross Liability	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	20,000,000		20,000,000
Recurring | Quoted Market Prices in Active Markets (Level 1) | Non-U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	569,000,000		378,000,000
Recurring | Quoted Market Prices in Active Markets (Level 1) | Other U.S. debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	20,000,000		20,000,000
Investment securities available for sale	0		0
Trading liabilities	4,000,000
Recurring | Quoted Market Prices in Active Markets (Level 1) | US Treasury and federal agencies, direct obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	12,418,000,000		10,056,000,000
Recurring | Quoted Market Prices in Active Markets (Level 1) | US Treasury and federal agencies, mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | Total asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | Asset-backed securities, student loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | Asset-backed securities, credit cards
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | Asset-backed securities, sub-prime
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | Asset-backed securities, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | Total non-U.S. debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | Non-U.S. debt securities, mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | Non-U.S. debt securities, asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | Government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | Non-U.S. debt securities, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | State and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | Collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | U.S. equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | Non-U.S. equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | U.S. money-market mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Quoted Market Prices in Active Markets (Level 1) | Non-U.S. money-market mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	536,000,000		506,000,000
Investment securities available for sale	79,023,000,000		79,491,000,000
Derivative Asset, Gross Asset	16,075,000,000		15,133,000,000
Assets, fair value disclosure	95,634,000,000		95,130,000,000
Derivative Liability, Gross Liability	17,216,000,000		15,151,000,000
Total liabilities carried at fair value	17,216,000,000		15,151,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Gross Asset	15,931,000,000		15,054,000,000
Derivative Liability, Gross Liability	16,881,000,000		14,851,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | Interest-rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Gross Asset	141,000,000		77,000,000
Derivative Liability, Gross Liability	232,000,000		239,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Gross Asset	3,000,000		2,000,000
Derivative Liability, Gross Liability	103,000,000		61,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	0		0
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | Non-U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	0		0
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | Other U.S. debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	536,000,000		506,000,000
Investment securities available for sale	4,064,000,000		4,100,000,000
Trading liabilities	0
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | US Treasury and federal agencies, direct obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	578,000,000		599,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | US Treasury and federal agencies, mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	21,046,000,000		20,714,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | Total asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	16,030,000,000		16,570,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | Asset-backed securities, student loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	11,807,000,000		12,201,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | Asset-backed securities, credit cards
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	2,917,000,000		3,053,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | Asset-backed securities, sub-prime
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	911,000,000		951,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | Asset-backed securities, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	395,000,000		365,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | Total non-U.S. debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	20,354,000,000		21,503,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | Non-U.S. debt securities, mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	8,621,000,000		9,606,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | Non-U.S. debt securities, asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	3,133,000,000		2,931,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | Government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	3,811,000,000		3,909,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | Non-U.S. debt securities, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	4,789,000,000		5,057,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | State and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	11,012,000,000		10,782,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | Collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	5,308,000,000		4,725,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | U.S. equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	39,000,000		39,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | Non-U.S. equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	2,000,000		2,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | U.S. money-market mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	582,000,000		449,000,000
Recurring | Pricing Methods with Significant Observable Market Inputs (Level 2) | Non-U.S. money-market mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	8,000,000		8,000,000
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	0		0
Investment securities available for sale	5,171,000,000		5,366,000,000
Derivative Asset, Gross Asset	185,000,000		81,000,000
Assets, fair value disclosure	5,356,000,000		5,447,000,000
Derivative Liability, Gross Liability	181,000,000		83,000,000
Total liabilities carried at fair value	181,000,000		83,000,000
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Gross Asset	185,000,000		81,000,000
Derivative Liability, Gross Liability	172,000,000		74,000,000
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Interest-rate contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Gross Asset	0		0
Derivative Liability, Gross Liability	0		0
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative Asset, Gross Asset	0		0
Derivative Liability, Gross Liability	9,000,000		9,000,000
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	0		0
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	0		0
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Other U.S. debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading account assets	0		0
Investment securities available for sale	9,000,000		9,000,000
Trading liabilities	0
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | US Treasury and federal agencies, direct obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | US Treasury and federal agencies, mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Total asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	3,890,000,000		4,039,000,000
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, student loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	257,000,000		259,000,000
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, credit cards
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, sub-prime
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	3,633,000,000		3,780,000,000
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Total non-U.S. debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	713,000,000		666,000,000
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. debt securities, mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	43,000,000		0
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. debt securities, asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	228,000,000		295,000,000
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Government securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. debt securities, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	442,000,000		371,000,000
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | State and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	37,000,000		38,000,000
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Collateralized mortgage obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	522,000,000		614,000,000
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | U.S. equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | U.S. money-market mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Recurring | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. money-market mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	0		0
Collateralized Loan Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	3,600,000,000		3,800,000,000
Automobile Loan Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	348,000,000		315,000,000
Non-US Debt Securities, Covered Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	3,300,000,000
Non-U.S. debt securities, other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available for sale	$1,100,000,000		$1,200,000,000

Fair_Value_Schedule_of_Fair_Va1

Fair Value - Schedule of Fair Value Measurements, Assets, Using Significant Unobservable Inputs (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	$5,447	$7,564
Recorded in Revenue, Assets	144	7
Recorded in Other Comprehensive Income, Assets	-11	-5
Purchases, Assets	483	93
Sales, Assets		-7
Settlements, Assets	-358	-366
Transfers out of Level 3, Assets	-349	-1,217
Fair value as of end of period	5,356	6,069
Change in Unrealized Gains (Losses) Related to Financial Instruments Held as of period end	107	-7
Derivative instruments, assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	81	19
Recorded in Revenue, Assets	131	-11
Recorded in Other Comprehensive Income, Assets	0	0
Purchases, Assets	36	7
Sales, Assets		0
Settlements, Assets	-63	-9
Transfers out of Level 3, Assets	0	0
Fair value as of end of period	185	6
Change in Unrealized Gains (Losses) Related to Financial Instruments Held as of period end	107	-7
Foreign exchange contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	81	19
Recorded in Revenue, Assets	131	-11
Recorded in Other Comprehensive Income, Assets	0	0
Purchases, Assets	36	7
Sales, Assets		0
Settlements, Assets	-63	-9
Transfers out of Level 3, Assets	0	0
Fair value as of end of period	185	6
Change in Unrealized Gains (Losses) Related to Financial Instruments Held as of period end	107	-7
Categories of investments, marketable securities, available-for-sale securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	5,366	7,545
Recorded in Revenue, Assets	13	18
Recorded in Other Comprehensive Income, Assets	-11	-5
Purchases, Assets	447	86
Sales, Assets		-7
Settlements, Assets	-295	-357
Transfers out of Level 3, Assets	-349	-1,217
Fair value as of end of period	5,171	6,063
Categories of investments, marketable securities, available-for-sale securities | US Treasury and federal agencies, mortgage-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period		716
Recorded in Revenue, Assets		0
Recorded in Other Comprehensive Income, Assets		0
Purchases, Assets		0
Sales, Assets		0
Settlements, Assets		-5
Transfers out of Level 3, Assets		-611
Fair value as of end of period		100
Categories of investments, marketable securities, available-for-sale securities | Total asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	4,039	4,979
Recorded in Revenue, Assets	12	16
Recorded in Other Comprehensive Income, Assets	-11	-3
Purchases, Assets	0	6
Sales, Assets		0
Settlements, Assets	-150	-282
Transfers out of Level 3, Assets	0	-79
Fair value as of end of period	3,890	4,637
Categories of investments, marketable securities, available-for-sale securities | Asset-backed securities, student loans
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	259	423
Recorded in Revenue, Assets	0	1
Recorded in Other Comprehensive Income, Assets	1	1
Purchases, Assets	0	0
Sales, Assets		0
Settlements, Assets	-3	-13
Transfers out of Level 3, Assets	0	-79
Fair value as of end of period	257	333
Categories of investments, marketable securities, available-for-sale securities | Asset-backed securities, credit cards
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period		24
Recorded in Revenue, Assets		0
Recorded in Other Comprehensive Income, Assets		0
Purchases, Assets		0
Sales, Assets		0
Settlements, Assets		-24
Transfers out of Level 3, Assets		0
Fair value as of end of period		0
Categories of investments, marketable securities, available-for-sale securities | Asset-backed securities, other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	3,780	4,532
Recorded in Revenue, Assets	12	15
Recorded in Other Comprehensive Income, Assets	-12	-4
Purchases, Assets	0	6
Sales, Assets		0
Settlements, Assets	-147	-245
Transfers out of Level 3, Assets	0	0
Fair value as of end of period	3,633	4,304
Categories of investments, marketable securities, available-for-sale securities | Total non-U.S. debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	666	1,637
Recorded in Revenue, Assets	1	2
Recorded in Other Comprehensive Income, Assets	1	-2
Purchases, Assets	154	0
Sales, Assets		-1
Settlements, Assets	-109	-63
Transfers out of Level 3, Assets	0	-499
Fair value as of end of period	713	1,074
Categories of investments, marketable securities, available-for-sale securities | Non-U.S. debt securities, mortgage-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	0	375
Recorded in Revenue, Assets	0	0
Recorded in Other Comprehensive Income, Assets	0	0
Purchases, Assets	43	0
Sales, Assets		0
Settlements, Assets	0	0
Transfers out of Level 3, Assets	0	-375
Fair value as of end of period	43	0
Categories of investments, marketable securities, available-for-sale securities | Non-U.S. debt securities, asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	295	798
Recorded in Revenue, Assets	1	2
Recorded in Other Comprehensive Income, Assets	0	-1
Purchases, Assets	0	0
Sales, Assets		0
Settlements, Assets	-68	-63
Transfers out of Level 3, Assets	0	-124
Fair value as of end of period	228	612
Categories of investments, marketable securities, available-for-sale securities | Non-U.S. debt securities, other
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	371	464
Recorded in Revenue, Assets	0	0
Recorded in Other Comprehensive Income, Assets	1	-1
Purchases, Assets	111	0
Sales, Assets		-1
Settlements, Assets	-41	0
Transfers out of Level 3, Assets	0	0
Fair value as of end of period	442	462
Categories of investments, marketable securities, available-for-sale securities | State and political subdivisions
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	38	43
Recorded in Revenue, Assets	0	0
Recorded in Other Comprehensive Income, Assets	-1	0
Purchases, Assets	0	0
Sales, Assets		0
Settlements, Assets	0	-1
Transfers out of Level 3, Assets	0	0
Fair value as of end of period	37	42
Categories of investments, marketable securities, available-for-sale securities | Collateralized mortgage obligations
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	614	162
Recorded in Revenue, Assets	0	0
Recorded in Other Comprehensive Income, Assets	0	0
Purchases, Assets	293	80
Sales, Assets		-6
Settlements, Assets	-36	-6
Transfers out of Level 3, Assets	-349	-28
Fair value as of end of period	522	202
Categories of investments, marketable securities, available-for-sale securities | Other U.S. debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value as of beginning of period	9	8
Recorded in Revenue, Assets	0	0
Recorded in Other Comprehensive Income, Assets	0	0
Purchases, Assets	0	0
Sales, Assets		0
Settlements, Assets	0	0
Transfers out of Level 3, Assets	0	0
Fair value as of end of period	$9	$8

Fair_Value_Schedule_of_Fair_Va2

Fair Value - Schedule of Fair Value Measurements, Liabilities, Using Significant Unobservable Inputs (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Liabilities	$83	$26
Recorded in Revenue, Liabilities	109	-10
Issuances, Liabilities	-37	-7
Settlements, Liabilities	-48	-6
Fair Value, ending balance, Liabilities	181	17
Change in Unrealized (Gains) Losses Related to Financial Instruments Held as of end of period	93	-5
Derivative instruments, liabilities | Accrued expenses and other liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Liabilities	83	26
Recorded in Revenue, Liabilities	109	-10
Issuances, Liabilities	-37	-7
Settlements, Liabilities	-48	-6
Fair Value, ending balance, Liabilities	181	17
Change in Unrealized (Gains) Losses Related to Financial Instruments Held as of end of period	93	-5
Foreign exchange contracts | Accrued expenses and other liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Liabilities	74	17
Recorded in Revenue, Liabilities	109	-10
Issuances, Liabilities	-37	-7
Settlements, Liabilities	-48	-6
Fair Value, ending balance, Liabilities	172	8
Change in Unrealized (Gains) Losses Related to Financial Instruments Held as of end of period	93	-5
Other | Accrued expenses and other liabilities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning balance, Liabilities	9	9
Recorded in Revenue, Liabilities	0	0
Issuances, Liabilities	0	0
Settlements, Liabilities	0	0
Fair Value, ending balance, Liabilities	9	9
Change in Unrealized (Gains) Losses Related to Financial Instruments Held as of end of period		$0

Fair_Value_Level_3_Total_Reali

Fair Value - Level 3 Total Realized And Unrealized Gains And Losses Recorded In Revenue (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Total Revenue [Member]
Realized and Unrealized Gains and Losses [Line Items]
Total Realized and Unrealized Gains (Losses) Recorded in Revenue	$35	$17
Change in Unrealized Gains (Losses) Related to Financial Instruments Held	14	-2
Trading services
Realized and Unrealized Gains and Losses [Line Items]
Total Realized and Unrealized Gains (Losses) Recorded in Revenue	22	-1
Change in Unrealized Gains (Losses) Related to Financial Instruments Held	14	-2
Total fee revenue
Realized and Unrealized Gains and Losses [Line Items]
Total Realized and Unrealized Gains (Losses) Recorded in Revenue	22	-1
Change in Unrealized Gains (Losses) Related to Financial Instruments Held	14	-2
Net interest revenue
Realized and Unrealized Gains and Losses [Line Items]
Total Realized and Unrealized Gains (Losses) Recorded in Revenue	13	18
Change in Unrealized Gains (Losses) Related to Financial Instruments Held	$0	$0

Fair_Value_Fair_Value_Inputs_A

Fair Value - Fair Value Inputs, Assets and Liabilities, Quantitative Information (Details) (USD $)	3 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	96,612	94,913
Asset-backed securities, student loans
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	12,064	12,460
Asset-backed securities, credit cards
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	2,917	3,053
Asset-backed securities, other
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	4,028	4,145
State and political subdivisions
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	11,049	10,820
Pricing Methods with Significant Unobservable Market Inputs (Level 3)
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Assets, fair value disclosure	5,356	5,447
Liabilities, fair value disclosure	181	83
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Derivative instruments, liabilities
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative instruments, foreign exchange contracts, liabilities	172	74
Derivative instruments, other, liabilities	9	9
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Derivative instruments, assets
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative instruments, foreign exchange contracts, assets	185	81
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, student loans
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	257	259
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, other
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	3,633	3,780
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | State and political subdivisions
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	37	38
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Discounted cash flows | Derivative instruments, liabilities | Weighted average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Participant redemptions	5.00%	5.20%
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Discounted cash flows | Asset-backed securities, other | Weighted average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Credit spread	0.20%	0.20%
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Discounted cash flows | State and political subdivisions | Weighted average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Credit spread	2.20%	2.10%
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Option model | Derivative instruments, liabilities | Weighted average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility	11.30%	9.00%
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Option model | Derivative instruments, assets | Weighted average
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Volatility	10.80%	9.10%
Significant Unobservable Inputs Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3)
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Assets, fair value disclosure	276	178
Liabilities, fair value disclosure	181	83
Significant Unobservable Inputs Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Derivative instruments, liabilities
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative instruments, foreign exchange contracts, liabilities	172	74
Derivative instruments, other, liabilities	9	9
Significant Unobservable Inputs Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Derivative instruments, assets
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Derivative instruments, foreign exchange contracts, assets	185	81
Significant Unobservable Inputs Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, student loans
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	0	0
Significant Unobservable Inputs Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, other
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	54	59
Significant Unobservable Inputs Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | State and political subdivisions
Fair Value Inputs, Assets and Liabilities, Quantitative Information [Line Items]
Investment securities available for sale	37	38

Fair_Value_Schedule_of_Availab

Fair Value - Schedule of Availability of Significant Unobservable Inputs by Balance Sheet Classification (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Assets:
Investment securities available for sale	$96,612	$94,913
Asset-backed securities, student loans
Assets:
Investment securities available for sale	12,064	12,460
Asset-backed securities, credit cards
Assets:
Investment securities available for sale	2,917	3,053
Asset-backed securities, other
Assets:
Investment securities available for sale	4,028	4,145
Non-U.S. debt securities, mortgage-backed securities
Assets:
Investment securities available for sale	8,664	9,606
Non-U.S. debt securities, asset-backed securities
Assets:
Investment securities available for sale	3,361	3,226
Non-U.S. debt securities, other
Assets:
Investment securities available for sale	5,231	5,428
State and political subdivisions
Assets:
Investment securities available for sale	11,049	10,820
Collateralized mortgage obligations
Assets:
Investment securities available for sale	5,830	5,339
Other U.S. debt securities
Assets:
Investment securities available for sale	4,073	4,109
Pricing Methods with Significant Unobservable Market Inputs (Level 3)
Assets:
Assets, fair value disclosure	5,356	5,447
Liabilities:
Liabilities, fair value disclosure	181	83
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Derivative instruments, liabilities
Liabilities:
Derivative instruments, foreign exchange contracts, liabilities	172	74
Derivative instruments, other, liabilities	9	9
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Derivative instruments, assets
Assets:
Derivative instruments, foreign exchange contracts, assets	185	81
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, student loans
Assets:
Investment securities available for sale	257	259
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, other
Assets:
Investment securities available for sale	3,633	3,780
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. debt securities, mortgage-backed securities
Assets:
Investment securities available for sale	43
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. debt securities, asset-backed securities
Assets:
Investment securities available for sale	228	295
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. debt securities, other
Assets:
Investment securities available for sale	442	371
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | State and political subdivisions
Assets:
Investment securities available for sale	37	38
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Collateralized mortgage obligations
Assets:
Investment securities available for sale	522	614
Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Other U.S. debt securities
Assets:
Investment securities available for sale	9	9
Significant Unobservable Inputs Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3)
Assets:
Assets, fair value disclosure	276	178
Liabilities:
Liabilities, fair value disclosure	181	83
Significant Unobservable Inputs Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Derivative instruments, liabilities
Liabilities:
Derivative instruments, foreign exchange contracts, liabilities	172	74
Derivative instruments, other, liabilities	9	9
Significant Unobservable Inputs Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Derivative instruments, assets
Assets:
Derivative instruments, foreign exchange contracts, assets	185	81
Significant Unobservable Inputs Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, student loans
Assets:
Investment securities available for sale	0	0
Significant Unobservable Inputs Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, other
Assets:
Investment securities available for sale	54	59
Significant Unobservable Inputs Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. debt securities, mortgage-backed securities
Assets:
Investment securities available for sale	0
Significant Unobservable Inputs Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. debt securities, asset-backed securities
Assets:
Investment securities available for sale	0	0
Significant Unobservable Inputs Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. debt securities, other
Assets:
Investment securities available for sale		0
Significant Unobservable Inputs Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | State and political subdivisions
Assets:
Investment securities available for sale	37	38
Significant Unobservable Inputs Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Collateralized mortgage obligations
Assets:
Investment securities available for sale	0	0
Significant Unobservable Inputs Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Other U.S. debt securities
Assets:
Investment securities available for sale	0	0
Significant Unobservable Inputs Not Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3)
Assets:
Assets, fair value disclosure	5,080	5,269
Liabilities:
Liabilities, fair value disclosure	0	0
Significant Unobservable Inputs Not Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Derivative instruments, liabilities
Liabilities:
Derivative instruments, foreign exchange contracts, liabilities	0	0
Derivative instruments, other, liabilities	0	0
Significant Unobservable Inputs Not Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Derivative instruments, assets
Assets:
Derivative instruments, foreign exchange contracts, assets	0	0
Significant Unobservable Inputs Not Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, student loans
Assets:
Investment securities available for sale	257	259
Significant Unobservable Inputs Not Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Asset-backed securities, other
Assets:
Investment securities available for sale	3,579	3,721
Significant Unobservable Inputs Not Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. debt securities, mortgage-backed securities
Assets:
Investment securities available for sale	43
Significant Unobservable Inputs Not Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. debt securities, asset-backed securities
Assets:
Investment securities available for sale	228	295
Significant Unobservable Inputs Not Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Non-U.S. debt securities, other
Assets:
Investment securities available for sale	442	371
Significant Unobservable Inputs Not Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | State and political subdivisions
Assets:
Investment securities available for sale	0	0
Significant Unobservable Inputs Not Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Collateralized mortgage obligations
Assets:
Investment securities available for sale	522	614
Significant Unobservable Inputs Not Readily Available | Pricing Methods with Significant Unobservable Market Inputs (Level 3) | Other U.S. debt securities
Assets:
Investment securities available for sale	$9	$9

Fair_Value_Carrying_Value_and_

Fair Value - Carrying Value and Estimated Fair Value of Financial Instruments (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Financial Assets:
Cash and due from banks	$3,149	$1,855	$3,877	$3,220
Interest-bearing deposits with banks	83,398	93,523
Securities purchased under resale agreements	11,331	2,390
Investment securities held to maturity, fair value	16,417	17,842
Net loans (excluding leases)	17,339	17,131
Financial Liabilities:
Noninterest-bearing	72,704	70,490
Interest-bearing—U.S.	30,769	33,012
Interest-bearing—non-U.S.	107,879	105,538
Securities sold under repurchase agreements	10,158	8,925
Federal funds purchased	17	21
Other short-term borrowings	4,346	4,381
Long-term debt	9,432	10,229
Reported Amount
Financial Assets:
Cash and due from banks	3,149	1,855
Interest-bearing deposits with banks	83,398	93,523
Securities purchased under resale agreements	11,331	2,390
Investment securities held to maturity, fair value	16,245	17,723
Net loans (excluding leases)	17,344	17,158
Financial Liabilities:
Noninterest-bearing	72,704	70,490
Interest-bearing—U.S.	30,769	33,012
Interest-bearing—non-U.S.	107,879	105,538
Securities sold under repurchase agreements	10,158	8,925
Federal funds purchased	17	21
Other short-term borrowings	4,346	4,381
Long-term debt	9,174	10,042
Quoted Market Prices in Active Markets (Level 1)
Financial Assets:
Cash and due from banks	3,149	1,855
Interest-bearing deposits with banks	0	0
Securities purchased under resale agreements	0	0
Investment securities held to maturity, fair value	0	0
Net loans (excluding leases)	0	0
Financial Liabilities:
Noninterest-bearing	0	0
Interest-bearing—U.S.	0	0
Interest-bearing—non-U.S.	0	0
Securities sold under repurchase agreements	0	0
Federal funds purchased	0	0
Other short-term borrowings	0	0
Long-term debt	0	0
Pricing Methods with Significant Observable Market Inputs (Level 2)
Financial Assets:
Cash and due from banks	0	0
Interest-bearing deposits with banks	83,398	93,523
Securities purchased under resale agreements	11,331	2,390
Investment securities held to maturity, fair value	16,417	17,842
Net loans (excluding leases)	17,177	16,964
Financial Liabilities:
Noninterest-bearing	72,704	70,490
Interest-bearing—U.S.	30,769	33,012
Interest-bearing—non-U.S.	107,879	105,538
Securities sold under repurchase agreements	10,158	8,925
Federal funds purchased	17	21
Other short-term borrowings	4,346	4,381
Long-term debt	8,592	9,382
Pricing Methods with Significant Unobservable Market Inputs (Level 3)
Financial Assets:
Cash and due from banks	0	0
Interest-bearing deposits with banks	0	0
Securities purchased under resale agreements	0	0
Investment securities held to maturity, fair value	0	0
Net loans (excluding leases)	162	167
Financial Liabilities:
Noninterest-bearing	0	0
Interest-bearing—U.S.	0	0
Interest-bearing—non-U.S.	0	0
Securities sold under repurchase agreements	0	0
Federal funds purchased	0	0
Other short-term borrowings	0	0
Long-term debt	$840	$847

Investment_Securities_Narrativ

Investment Securities - Narrative (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
	security
Investments, Debt and Equity Securities [Abstract]
Pledged Financial Instruments, Not Separately Reported, Securities	$43,000,000,000		$44,020,000,000
Other-than-temporary impairment recorded	1,000,000	9,000,000
Impairment associated with adverse changes in timing of expected future cash flows	1,000,000	0
Impairment associated with expected credit losses	0	9,000,000
Gross pre-tax unrealized losses on securities	$442,000,000
Number of available for sale and held to maturity securities in gross pre-tax unrealized loss position	1,189

Investment_Securities_Schedule

Investment Securities - Schedule of Marketable Securities (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	95,524	$94,108
Available for sale, gross unrealized gains	1,429	1,229
Available for sale, gross unrealized losses	341	424
Investment securities available for sale	96,612	94,913
Held to maturity, amortized cost	16,245	17,723
Held to maturity, gross unrealized gains	273	309
Held to maturity, gross unrealized losses	101	190
Held to maturity, fair value	16,417	17,842
Total asset-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	19,922	20,615
Available for sale, gross unrealized gains	209	218
Available for sale, gross unrealized losses	211	224
Investment securities available for sale	19,920	20,609
Held to maturity, amortized cost	3,197	3,288
Held to maturity, gross unrealized gains	8	7
Held to maturity, gross unrealized losses	5	5
Held to maturity, fair value	3,200	3,290
US Treasury and federal agencies, direct obligations
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	12,803	10,573
Available for sale, gross unrealized gains	194	83
Available for sale, gross unrealized losses	1	1
Investment securities available for sale	12,996	10,655
Held to maturity, amortized cost	5,112	5,114
Held to maturity, gross unrealized gains	0	0
Held to maturity, gross unrealized losses	69	147
Held to maturity, fair value	5,043	4,967
US Treasury and federal agencies, mortgage-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	20,861	20,648
Available for sale, gross unrealized gains	251	193
Available for sale, gross unrealized losses	66	127
Investment securities available for sale	21,046	20,714
Held to maturity, amortized cost	57	62
Held to maturity, gross unrealized gains	4	4
Held to maturity, gross unrealized losses	0	0
Held to maturity, fair value	61	66
Asset-backed securities, student loans
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	12,070	12,478
Available for sale, gross unrealized gains	107	106
Available for sale, gross unrealized losses	113	124
Investment securities available for sale	12,064	12,460
Held to maturity, amortized cost	1,755	1,814
Held to maturity, gross unrealized gains	3	2
Held to maturity, gross unrealized losses	5	4
Held to maturity, fair value	1,753	1,812
Asset-backed securities, credit cards
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	2,941	3,077
Available for sale, gross unrealized gains	10	10
Available for sale, gross unrealized losses	34	34
Investment securities available for sale	2,917	3,053
Held to maturity, amortized cost	897	897
Held to maturity, gross unrealized gains	2	2
Held to maturity, gross unrealized losses	0	0
Held to maturity, fair value	899	899
Asset-backed securities, sub-prime
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	961	1,005
Available for sale, gross unrealized gains	2	2
Available for sale, gross unrealized losses	52	56
Investment securities available for sale	911	951
Asset-backed securities, other
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	3,950	4,055
Available for sale, gross unrealized gains	90	100
Available for sale, gross unrealized losses	12	10
Investment securities available for sale	4,028	4,145
Held to maturity, amortized cost	545	577
Held to maturity, gross unrealized gains	3	3
Held to maturity, gross unrealized losses	0	1
Held to maturity, fair value	548	579
Total non-U.S. debt securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	20,861	21,939
Available for sale, gross unrealized gains	216	241
Available for sale, gross unrealized losses	10	11
Investment securities available for sale	21,067	22,169
Held to maturity, amortized cost	5,786	6,881
Held to maturity, gross unrealized gains	165	191
Held to maturity, gross unrealized losses	19	23
Held to maturity, fair value	5,932	7,049
Non-U.S. debt securities, mortgage-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	8,522	9,442
Available for sale, gross unrealized gains	146	168
Available for sale, gross unrealized losses	4	4
Investment securities available for sale	8,664	9,606
Held to maturity, amortized cost	3,275	3,787
Held to maturity, gross unrealized gains	154	177
Held to maturity, gross unrealized losses	19	22
Held to maturity, fair value	3,410	3,942
Non-U.S. debt securities, asset-backed securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	3,353	3,215
Available for sale, gross unrealized gains	9	11
Available for sale, gross unrealized losses	1	0
Investment securities available for sale	3,361	3,226
Held to maturity, amortized cost	2,298	2,868
Held to maturity, gross unrealized gains	11	14
Held to maturity, gross unrealized losses	0	1
Held to maturity, fair value	2,309	2,881
Government securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	3,800	3,899
Available for sale, gross unrealized gains	11	10
Available for sale, gross unrealized losses	0	0
Investment securities available for sale	3,811	3,909
Held to maturity, amortized cost	148	154
Held to maturity, gross unrealized gains	0	0
Held to maturity, gross unrealized losses	0	0
Held to maturity, fair value	148	154
Non-U.S. debt securities, other
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	5,186	5,383
Available for sale, gross unrealized gains	50	52
Available for sale, gross unrealized losses	5	7
Investment securities available for sale	5,231	5,428
Held to maturity, amortized cost	65	72
Held to maturity, gross unrealized gains	0	0
Held to maturity, gross unrealized losses	0	0
Held to maturity, fair value	65	72
State and political subdivisions
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	10,729	10,532
Available for sale, gross unrealized gains	357	325
Available for sale, gross unrealized losses	37	37
Investment securities available for sale	11,049	10,820
Held to maturity, amortized cost	3	9
Held to maturity, gross unrealized gains	0	0
Held to maturity, gross unrealized losses	0	0
Held to maturity, fair value	3	9
Collateralized mortgage obligations
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	5,738	5,280
Available for sale, gross unrealized gains	99	71
Available for sale, gross unrealized losses	7	12
Investment securities available for sale	5,830	5,339
Held to maturity, amortized cost	2,090	2,369
Held to maturity, gross unrealized gains	96	107
Held to maturity, gross unrealized losses	8	15
Held to maturity, fair value	2,178	2,461
Other U.S. debt securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	3,987	4,033
Available for sale, gross unrealized gains	94	88
Available for sale, gross unrealized losses	8	12
Investment securities available for sale	4,073	4,109
U.S. equity securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	31	29
Available for sale, gross unrealized gains	9	10
Available for sale, gross unrealized losses	1	0
Investment securities available for sale	39	39
Non-U.S. equity securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	2	2
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	0	0
Investment securities available for sale	2	2
U.S. money-market mutual funds
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	582	449
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	0	0
Investment securities available for sale	582	449
Non-U.S. money-market mutual funds
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Available for sale, amortized cost	8	8
Available for sale, gross unrealized gains	0	0
Available for sale, gross unrealized losses	0	0
Investment securities available for sale	8	8
Federal Family Education Loan Program
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Federal government credit support guarantee, percentage minimum	97.00%
Collateralized Loan Obligations
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Investment securities available for sale	3,600	3,800
Automobile Loan Securities
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Investment securities available for sale	348	315
Non-US Debt Securities, Covered Bonds
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Investment securities available for sale	3,300
Non-U.S. debt securities, other
Available-For-Sale and Held-To-Maturity-Securities [Line Items]
Investment securities available for sale	1,100	$1,200

Investment_Securities_Schedule1

Investment Securities - Schedule of Gross Pre-Tax Unrealized Losses on Investment Securities (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	$7,819	$8,532
Available for sale, Gross Unrealized Losses Less than 12 months	41	39
Available for sale, Fair Value 12 months or longer	13,762	16,983
Available for sale, Gross Unrealized Losses 12 months or longer	300	385
Available for sale, Fair Value Total	21,581	25,515
Available for sale, Gross Unrealized Losses Total	341	424
Held to maturity, Fair Value Less than 12 months	3,482	2,608
Held-to-maturity, Gross, Less than 12 Months	21	13
Held to maturity, Fair Value 12 months or longer	4,197	6,220
Held to maturity, Gross Unrealized Losses 12 months or longer	80	177
Held to maturity, Fair Value Total	7,679	8,828
Held to maturity, Gross Unrealized Losses Total	101	190
Asset-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	2,284	2,364
Available for sale, Gross Unrealized Losses Less than 12 months	18	17
Available for sale, Fair Value 12 months or longer	7,662	7,982
Available for sale, Gross Unrealized Losses 12 months or longer	193	207
Available for sale, Fair Value Total	9,946	10,346
Available for sale, Gross Unrealized Losses Total	211	224
Held to maturity, Fair Value Less than 12 months	631	904
Held-to-maturity, Gross, Less than 12 Months	3	4
Held to maturity, Fair Value 12 months or longer	232	192
Held to maturity, Gross Unrealized Losses 12 months or longer	2	1
Held to maturity, Fair Value Total	863	1,096
Held to maturity, Gross Unrealized Losses Total	5	5
US Treasury and federal agencies, direct obligations
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	0	0
Available for sale, Gross Unrealized Losses Less than 12 months	0	0
Available for sale, Fair Value 12 months or longer	158	167
Available for sale, Gross Unrealized Losses 12 months or longer	1	1
Available for sale, Fair Value Total	158	167
Available for sale, Gross Unrealized Losses Total	1	1
Held to maturity, Fair Value Less than 12 months	2,062	76
Held-to-maturity, Gross, Less than 12 Months	13	1
Held to maturity, Fair Value 12 months or longer	2,981	4,891
Held to maturity, Gross Unrealized Losses 12 months or longer	56	146
Held to maturity, Fair Value Total	5,043	4,967
Held to maturity, Gross Unrealized Losses Total	69	147
US Treasury and federal agencies, mortgage-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	1,565	2,569
Available for sale, Gross Unrealized Losses Less than 12 months	8	9
Available for sale, Fair Value 12 months or longer	4,373	6,466
Available for sale, Gross Unrealized Losses 12 months or longer	58	118
Available for sale, Fair Value Total	5,938	9,035
Available for sale, Gross Unrealized Losses Total	66	127
Asset-backed securities, student loans
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	1,440	1,473
Available for sale, Gross Unrealized Losses Less than 12 months	13	15
Available for sale, Fair Value 12 months or longer	4,875	5,025
Available for sale, Gross Unrealized Losses 12 months or longer	100	109
Available for sale, Fair Value Total	6,315	6,498
Available for sale, Gross Unrealized Losses Total	113	124
Held to maturity, Fair Value Less than 12 months	631	780
Held-to-maturity, Gross, Less than 12 Months	3	3
Held to maturity, Fair Value 12 months or longer	232	192
Held to maturity, Gross Unrealized Losses 12 months or longer	2	1
Held to maturity, Fair Value Total	863	972
Held to maturity, Gross Unrealized Losses Total	5	4
Asset-backed securities, credit cards
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	0	344
Available for sale, Gross Unrealized Losses Less than 12 months	0	1
Available for sale, Fair Value 12 months or longer	1,287	1,270
Available for sale, Gross Unrealized Losses 12 months or longer	34	33
Available for sale, Fair Value Total	1,287	1,614
Available for sale, Gross Unrealized Losses Total	34	34
Held to maturity, Fair Value Less than 12 months		124
Held-to-maturity, Gross, Less than 12 Months		1
Held to maturity, Fair Value 12 months or longer		0
Held to maturity, Gross Unrealized Losses 12 months or longer		0
Held to maturity, Fair Value Total		124
Held to maturity, Gross Unrealized Losses Total		1
Asset-backed securities, sub-prime
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	0	0
Available for sale, Gross Unrealized Losses Less than 12 months	0	0
Available for sale, Fair Value 12 months or longer	860	896
Available for sale, Gross Unrealized Losses 12 months or longer	52	56
Available for sale, Fair Value Total	860	896
Available for sale, Gross Unrealized Losses Total	52	56
Asset-backed securities, other
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	844	547
Available for sale, Gross Unrealized Losses Less than 12 months	5	1
Available for sale, Fair Value 12 months or longer	640	791
Available for sale, Gross Unrealized Losses 12 months or longer	7	9
Available for sale, Fair Value Total	1,484	1,338
Available for sale, Gross Unrealized Losses Total	12	10
Total non-U.S. debt securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	2,237	1,931
Available for sale, Gross Unrealized Losses Less than 12 months	6	6
Available for sale, Fair Value 12 months or longer	439	498
Available for sale, Gross Unrealized Losses 12 months or longer	4	5
Available for sale, Fair Value Total	2,676	2,429
Available for sale, Gross Unrealized Losses Total	10	11
Held to maturity, Fair Value Less than 12 months	517	1,206
Held-to-maturity, Gross, Less than 12 Months	2	4
Held to maturity, Fair Value 12 months or longer	569	590
Held to maturity, Gross Unrealized Losses 12 months or longer	17	19
Held to maturity, Fair Value Total	1,086	1,796
Held to maturity, Gross Unrealized Losses Total	19	23
Non-U.S. debt securities, mortgage-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	1,097	1,350
Available for sale, Gross Unrealized Losses Less than 12 months	3	2
Available for sale, Fair Value 12 months or longer	146	170
Available for sale, Gross Unrealized Losses 12 months or longer	1	2
Available for sale, Fair Value Total	1,243	1,520
Available for sale, Gross Unrealized Losses Total	4	4
Held to maturity, Fair Value Less than 12 months	517	507
Held-to-maturity, Gross, Less than 12 Months	2	3
Held to maturity, Fair Value 12 months or longer	569	590
Held to maturity, Gross Unrealized Losses 12 months or longer	17	19
Held to maturity, Fair Value Total	1,086	1,097
Held to maturity, Gross Unrealized Losses Total	19	22
Non-U.S. debt securities, asset-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	499
Available for sale, Gross Unrealized Losses Less than 12 months	1
Available for sale, Fair Value 12 months or longer	0
Available for sale, Gross Unrealized Losses 12 months or longer	0
Available for sale, Fair Value Total	499
Available for sale, Gross Unrealized Losses Total	1
Held to maturity, Fair Value Less than 12 months		699
Held-to-maturity, Gross, Less than 12 Months		1
Held to maturity, Fair Value 12 months or longer		0
Held to maturity, Gross Unrealized Losses 12 months or longer		0
Held to maturity, Fair Value Total		699
Held to maturity, Gross Unrealized Losses Total		1
Non-U.S. debt securities, other
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	641	581
Available for sale, Gross Unrealized Losses Less than 12 months	2	4
Available for sale, Fair Value 12 months or longer	293	328
Available for sale, Gross Unrealized Losses 12 months or longer	3	3
Available for sale, Fair Value Total	934	909
Available for sale, Gross Unrealized Losses Total	5	7
State and political subdivisions
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	980	610
Available for sale, Gross Unrealized Losses Less than 12 months	6	3
Available for sale, Fair Value 12 months or longer	776	1,315
Available for sale, Gross Unrealized Losses 12 months or longer	31	34
Available for sale, Fair Value Total	1,756	1,925
Available for sale, Gross Unrealized Losses Total	37	37
Collateralized mortgage obligations
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	747	731
Available for sale, Gross Unrealized Losses Less than 12 months	2	2
Available for sale, Fair Value 12 months or longer	208	311
Available for sale, Gross Unrealized Losses 12 months or longer	5	10
Available for sale, Fair Value Total	955	1,042
Available for sale, Gross Unrealized Losses Total	7	12
Held to maturity, Fair Value Less than 12 months	272	422
Held-to-maturity, Gross, Less than 12 Months	3	4
Held to maturity, Fair Value 12 months or longer	415	547
Held to maturity, Gross Unrealized Losses 12 months or longer	5	11
Held to maturity, Fair Value Total	687	969
Held to maturity, Gross Unrealized Losses Total	8	15
Other U.S. debt securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	0	327
Available for sale, Gross Unrealized Losses Less than 12 months	0	2
Available for sale, Fair Value 12 months or longer	146	244
Available for sale, Gross Unrealized Losses 12 months or longer	8	10
Available for sale, Fair Value Total	146	571
Available for sale, Gross Unrealized Losses Total	8	12
U.S. equity securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, Fair Value Less than 12 months	6
Available for sale, Gross Unrealized Losses Less than 12 months	1
Available for sale, Fair Value 12 months or longer	0
Available for sale, Gross Unrealized Losses 12 months or longer	0
Available for sale, Fair Value Total	6
Available for sale, Gross Unrealized Losses Total	$1

Investment_Securities_Schedule2

Investment Securities - Schedule of Contractual Maturities of Debt Securities (Details) (USD $)	Mar. 31, 2015
In Millions, unless otherwise specified
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	$8,762
Available for sale, 1 to 5 Years	37,637
Available for sale, 6 to 10 Years	21,303
Available for sale, Over 10 Years	28,279
Held to maturity, Under 1 Year	1,255
Held to maturity, 1 to 5 Years	4,225
Held to maturity, 6 to 10 Years	6,853
Held to maturity, Over 10 Years	3,912
Total asset-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	958
Available for sale, 1 to 5 Years	8,371
Available for sale, 6 to 10 Years	6,339
Available for sale, Over 10 Years	4,252
Held to maturity, Under 1 Year	13
Held to maturity, 1 to 5 Years	927
Held to maturity, 6 to 10 Years	1,041
Held to maturity, Over 10 Years	1,216
US Treasury and federal agencies, direct obligations
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	1
Available for sale, 1 to 5 Years	9,246
Available for sale, 6 to 10 Years	3,238
Available for sale, Over 10 Years	511
Held to maturity, Under 1 Year	0
Held to maturity, 1 to 5 Years	0
Held to maturity, 6 to 10 Years	4,999
Held to maturity, Over 10 Years	113
US Treasury and federal agencies, mortgage-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	117
Available for sale, 1 to 5 Years	2,420
Available for sale, 6 to 10 Years	4,056
Available for sale, Over 10 Years	14,453
Held to maturity, Under 1 Year	0
Held to maturity, 1 to 5 Years	11
Held to maturity, 6 to 10 Years	11
Held to maturity, Over 10 Years	35
Asset-backed securities, student loans
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	553
Available for sale, 1 to 5 Years	5,858
Available for sale, 6 to 10 Years	3,816
Available for sale, Over 10 Years	1,837
Held to maturity, Under 1 Year	4
Held to maturity, 1 to 5 Years	182
Held to maturity, 6 to 10 Years	357
Held to maturity, Over 10 Years	1,212
Asset-backed securities, credit cards
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	227
Available for sale, 1 to 5 Years	1,565
Available for sale, 6 to 10 Years	1,125
Available for sale, Over 10 Years	0
Held to maturity, Under 1 Year	0
Held to maturity, 1 to 5 Years	375
Held to maturity, 6 to 10 Years	522
Held to maturity, Over 10 Years	0
Asset-backed securities, sub-prime
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	8
Available for sale, 1 to 5 Years	7
Available for sale, 6 to 10 Years	0
Available for sale, Over 10 Years	896
Asset-backed securities, other
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	170
Available for sale, 1 to 5 Years	941
Available for sale, 6 to 10 Years	1,398
Available for sale, Over 10 Years	1,519
Held to maturity, Under 1 Year	9
Held to maturity, 1 to 5 Years	370
Held to maturity, 6 to 10 Years	162
Held to maturity, Over 10 Years	4
Total non-U.S. debt securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	5,627
Available for sale, 1 to 5 Years	11,034
Available for sale, 6 to 10 Years	1,364
Available for sale, Over 10 Years	3,042
Held to maturity, Under 1 Year	756
Held to maturity, 1 to 5 Years	2,997
Held to maturity, 6 to 10 Years	306
Held to maturity, Over 10 Years	1,727
Non-U.S. debt securities, mortgage-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	1,661
Available for sale, 1 to 5 Years	3,511
Available for sale, 6 to 10 Years	513
Available for sale, Over 10 Years	2,979
Held to maturity, Under 1 Year	476
Held to maturity, 1 to 5 Years	939
Held to maturity, 6 to 10 Years	133
Held to maturity, Over 10 Years	1,727
Non-U.S. debt securities, asset-backed securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	390
Available for sale, 1 to 5 Years	2,796
Available for sale, 6 to 10 Years	112
Available for sale, Over 10 Years	63
Held to maturity, Under 1 Year	132
Held to maturity, 1 to 5 Years	1,993
Held to maturity, 6 to 10 Years	173
Held to maturity, Over 10 Years	0
Government securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	2,236
Available for sale, 1 to 5 Years	1,575
Available for sale, 6 to 10 Years	0
Available for sale, Over 10 Years	0
Held to maturity, Under 1 Year	148
Held to maturity, 1 to 5 Years	0
Held to maturity, 6 to 10 Years	0
Held to maturity, Over 10 Years	0
Non-U.S. debt securities, other
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	1,340
Available for sale, 1 to 5 Years	3,152
Available for sale, 6 to 10 Years	739
Available for sale, Over 10 Years	0
Held to maturity, Under 1 Year	0
Held to maturity, 1 to 5 Years	65
Held to maturity, 6 to 10 Years	0
Held to maturity, Over 10 Years	0
State and political subdivisions
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	723
Available for sale, 1 to 5 Years	2,848
Available for sale, 6 to 10 Years	4,952
Available for sale, Over 10 Years	2,526
Held to maturity, Under 1 Year	3
Held to maturity, 1 to 5 Years	0
Held to maturity, 6 to 10 Years	0
Held to maturity, Over 10 Years	0
Collateralized mortgage obligations
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	249
Available for sale, 1 to 5 Years	1,044
Available for sale, 6 to 10 Years	1,077
Available for sale, Over 10 Years	3,460
Held to maturity, Under 1 Year	483
Held to maturity, 1 to 5 Years	290
Held to maturity, 6 to 10 Years	496
Held to maturity, Over 10 Years	821
Other U.S. debt securities
Contractual Maturities Of Debt Investment Securities [Line Items]
Available for sale, Under 1 Year	1,087
Available for sale, 1 to 5 Years	2,674
Available for sale, 6 to 10 Years	277
Available for sale, Over 10 Years	$35

Investment_Securities_Gains_an

Investment Securities - Gains and Losses Related to Investment Securities (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Gross realized gains from sales of available-for-sale securities	$0	$15
Gross realized losses from sales of available-for-sale securities(1)	0	0
Gross losses from other-than-temporary impairment	-1	-1
Losses reclassified (from) to other comprehensive income, or OCI	0	-8
Gains (losses) related to investment securities, net	-1	6
Impairment associated with expected credit losses	0	-9
Impairment associated with management's intent to sell impaired securities prior to recovery in value	0	0
Impairment associated with adverse changes in timing of expected future cash flows	-1	0
Net impairment losses	($1)	($9)

Investment_Securities_Schedule3

Investment Securities - Schedule of Credit-Related Loss Activity Recognized In Earnings (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance, beginning of period	$115	$122
Losses for which other-than-temporary impairment was not previously recognized	0	9
Losses for which other-than-temporary impairment was previously recognized	1	0
Previously recognized losses related to securities sold or matured	-9	-1
Losses related to securities intended or required to be sold	0	-6
Balance, end of period	$107	$124

Loans_and_Leases_Narrative_Det

Loans and Leases - Narrative (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
	loan		loan
Financing Receivable, Recorded Investment [Line Items]
Aggregate short-duration advances	$4,080,000,000		$3,540,000,000
Loans and leases, allowance for losses	41,000,000		38,000,000
Loans modified in troubled debt restructurings	0		0
Provision for loan losses	4,000,000	2,000,000
Institutional
Financing Receivable, Recorded Investment [Line Items]
Loans more than 90 days past due	0		0
Institutional | Senior Secured Bank Loans
Financing Receivable, Recorded Investment [Line Items]
Commercial and financial	2,530,000,000		2,070,000,000
Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Loans more than 90 days past due	0		0
Commercial and Financial
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, allowance for losses	11,000,000
Commercial and Financial | Senior Secured Bank Loans
Financing Receivable, Recorded Investment [Line Items]
Loans and leases, allowance for losses	$30,000,000		$26,000,000

Loans_and_Leases_Net_Loans_Det

Loans and Leases - Net Loans (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$18,319	$18,199
Allowance for loan losses	-41	-38
Loans and leases, net of allowance for loan losses	18,278	18,161
Institutional
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	18,284	18,171
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	35	28
U.S. | Institutional
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investment funds	11,228	11,388
Commercial and financial	3,294	3,061
Purchased receivables	115	124
Lease financing	334	335
U.S. | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial real estate	35	28
Non-U.S. | Institutional
Accounts, Notes, Loans and Financing Receivable [Line Items]
Investment funds	2,232	2,333
Commercial and financial	468	256
Purchased receivables	4	6
Lease financing	$609	$668

Loans_and_Leases_Recorded_Inve

Loans and Leases - Recorded Investment in Each Class of Total Loans and Leases by Credit Quality Indicator (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	$18,319	$18,199
Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	13,460	13,721
Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	3,762	3,317
Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	119	130
Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	943	1,003
Property Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	7	0
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	28	28
Investment grade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	15,546	15,421
Investment grade | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	13,351	13,304
Investment grade | Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	1,132	1,011
Investment grade | Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	119	130
Investment grade | Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	916	976
Investment grade | Property Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	0	0
Investment grade | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	28	0
Speculative
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	2,773	2,778
Speculative | Investment Funds
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	109	417
Speculative | Commercial and Financial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	2,630	2,306
Speculative | Purchased Receivables
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	0	0
Speculative | Lease Financing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	27	27
Speculative | Property Development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	7	0
Speculative | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases	$0	$28

Loans_and_Leases_Schedule_of_A

Loans and Leases - Schedule of Allowance for Loan Losses (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Evaluated for Impairment	$18,319	$18,199
Institutional
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Evaluated for Impairment	18,284	18,171
Amount of loan losses related to institutional loans collectively evaluated for impairment	41	38
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Evaluated for Impairment	35	28
Collectively Evaluated for Impairment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Evaluated for Impairment	18,319	18,199
Collectively Evaluated for Impairment | Institutional
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Evaluated for Impairment	18,284	18,171
Collectively Evaluated for Impairment | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Evaluated for Impairment	$35	$28

Loans_and_Leases_Impaired_Loan

Loans and Leases - Impaired Loans (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
CRE - property development - acquired credit impaired
Financing Receivable, Impaired [Line Items]
Recorded investment with no related allowance	$0	$0
Unpaid principal balance with no related allowance recorded	34	34
CRE - other - acquired credit impaired
Financing Receivable, Impaired [Line Items]
Recorded investment with no related allowance	0	0
Unpaid principal balance with no related allowance recorded	22	22
Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Recorded investment with no related allowance	0	0
Unpaid principal balance with no related allowance recorded	$56	$56

Loans_and_Leases_Schedule_of_A1

Loans and Leases - Schedule of Activity In The Allowance For Loan Losses (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$37	$28
Provisions	4	2
Ending balance	$41	$30

Goodwill_and_Other_Intangible_2

Goodwill and Other Intangible Assets - Changes In The Carrying Amount Of Goodwill (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Goodwill [Roll Forward]
Beginning balance	$5,826	$6,036
Foreign currency translation and other, net	-163	2
Ending balance	5,663	6,038
Investment Servicing
Goodwill [Roll Forward]
Beginning balance	5,793	5,999
Foreign currency translation and other, net	-160	2
Ending balance	5,633	6,001
Investment Management
Goodwill [Roll Forward]
Beginning balance	33	37
Foreign currency translation and other, net	-3	0
Ending balance	$30	$37

Goodwill_and_Other_Intangible_3

Goodwill and Other Intangible Assets - Changes In The Carrying Amount Of Other Intangible Assets (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	$2,025	$2,360
Amortization	-50	-54
Foreign currency translation and other, net	-83	0
Ending balance	1,892	2,306
Investment Servicing
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	1,998	2,321
Amortization	-48	-52
Foreign currency translation and other, net	-81	0
Ending balance	1,869	2,269
Investment Management
Finite-lived Intangible Assets [Roll Forward]
Beginning balance	27	39
Amortization	-2	-2
Foreign currency translation and other, net	-2	0
Ending balance	$23	$37

Goodwill_and_Other_Intangible_4

Goodwill and Other Intangible Assets - Gross Carrying Amount, Accumulated Amortization And Net Carrying Amount Of Other Intangible Assets (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$3,305	$3,471
Accumulated Amortization	-1,413	-1,446
Net Carrying Amount	1,892	2,025	2,306	2,360
Client relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	2,471	2,569
Accumulated Amortization	-1,087	-1,088
Net Carrying Amount	1,384	1,481
Core deposits
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	664	688
Accumulated Amortization	-220	-219
Net Carrying Amount	444	469
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	170	214
Accumulated Amortization	-106	-139
Net Carrying Amount	$64	$75

Other_Assets_Components_of_Oth

Other Assets - Components of Other Assets (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Other Assets [Line Items]
Total	$37,549	$32,600
Real estate acquired through foreclosure	63	62
Reported Amount | Other assets
Other Assets [Line Items]
Collateral deposits, net	22,094	18,134
Unrealized gains on derivative financial instruments, net	8,048	7,934
Bank-owned life insurance	2,419	2,402
Investments in joint ventures and other unconsolidated entities	1,875	1,798
Accounts receivable	1,087	513
Receivable for securities settlement	419	218
Prepaid expenses	376	259
Income taxes receivable	295	396
Deferred tax assets, net of valuation allowance	189	214
Deposits with clearing organizations	181	197
Receivable for securities sold	45	0
Other	521	535
Total	$37,549	$32,600

Commitments_and_Guarantees_Nar

Commitments and Guarantees - Narrative (Details) (USD $)	3 Months Ended
In Billions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Loss Contingencies [Line Items]
Unfunded commitments to extend credit	$23.88	$24.43
Unfunded commitments to extend credit, short term	78.00%
Unfunded Commitment to Extend Credit, Term	1 year
Cash collateral provided for securities lending	19.85	15.94
Accrued expenses and other liabilities
Loss Contingencies [Line Items]
Cash collateral received in connection to securities finance activities	$6.96	$6.48

Commitments_and_Guarantees_Con

Commitments and Guarantees - Contractual Amounts of Credit-Related Off-Balance Sheet Financial Instruments (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Commitments and Contingencies Disclosure [Abstract]
Indemnified securities financing	$348,960	$349,766
Stable value protection	23,425	23,409
Asset purchase agreements	4,212	4,107
Standby letters of credit	$4,782	$4,720

Commitments_and_Guarantees_Sch

Commitments and Guarantees - Schedule Of Repurchase Agreements (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Commitments and Contingencies Disclosure [Abstract]
Fair value of indemnified securities financing	$348,960	$349,766
Fair value of cash and securities held by us, as agent, as collateral for indemnified securities financing	364,212	364,411
Fair value of collateral for indemnified securities financing invested in indemnified repurchase agreements	78,163	85,309
Fair value of cash and securities held by us or our agents as collateral for investments in indemnified repurchase agreements	$83,256	$90,819

Contingencies_Narrative_Detail

Contingencies - Narrative (Details)

3 Months Ended

12 Months Ended

0 Months Ended

1 Months Ended

3 Months Ended

1 Months Ended

1 Months Ended

In Millions, unless otherwise specified

Mar. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Dec. 31, 2009

Dec. 31, 2008

Aug. 31, 2009

Aug. 31, 2009

Mar. 31, 2015

Oct. 31, 2009

Mar. 31, 2015

Mar. 31, 2015

Jan. 31, 2014

Mar. 31, 2015

Mar. 31, 2015

Jan. 31, 2014

Jan. 31, 2014

Mar. 31, 2015

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Securities Finance

Securities Finance

Foreign Exchange

Foreign Exchange

Putative Class Action

Transition Management

Transition Management

Transition Management

Transition Management

Transition Management

Investment Servicing

USD ($)

USD ($)

USD ($)

USD ($)

claim

claim

USD ($)

Legal Reserve

Regulatory Matter

Regulatory Matter

USD ($)

USD ($)

USD ($)

GBP (£)

claim

Loss Contingencies [Line Items]

Legal reserves

$358

Number of lawsuits from related participants of agency securities lending program

2

Loss contingency, damages sought, value

125

Litigation reserve

11

2.7

4.3

Realized loss on sales of securities

10

Actual damages asserted by attorney general

100

Number of pending claims

2

1

Estimated indirect foreign exchange revenue

68

246

285

248

331

336

369

462

Loss Contingency, Estimate of Possible Loss

335

Loss Contingency, Estimate Of Possible Loss, net of tax

150

Settlement, amount

$925

$37.80

£ 22.9

Claims settled

6

Contingencies_Tax_Contingencie

Contingencies Tax Contingencies (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits	$163	$163

Variable_Interest_Entities_Nar

Variable Interest Entities - Narrative (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Variable Interest Entities [Abstract]
Investment securities related to state and political subdivisions	$2,240,000,000		$2,270,000,000
Variable interest entity, other short-term borrowings	1,840,000,000		1,870,000,000
Weighted average life of trusts (in years)	5 years 8 months 15 days	5 years 10 months 18 days
Total standby bond-purchase agreement committed to trusts	1,880,000,000
Total letters of credit committed to trusts	669,000,000
Standby purchase agreements and letters of credit commitments utilized	0
Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	68,000,000		65,000,000
Liabilities	14,000,000		13,000,000
Potential maximum loss exposure of unconsolidated funds	54,000,000
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Potential maximum loss exposure of unconsolidated funds	$88,070,000		$45,100,000

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Income - Narrative (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Equity, Class of Treasury Stock [Line Items]
Preferred stock cash dividend	$31,000,000	$6,000,000
Cash dividends declared (in dollars per share)	$0.30	$0.26
Common stock dividends	-124,000,000	-112,000,000
March 2015 Share Repurchase
Equity, Class of Treasury Stock [Line Items]
Amount of common stock authorized for repurchase	1,800,000,000
Stock Repurchased During Period, Shares	0
March 2014 Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock Repurchased During Period, Shares	6,300,000
Treasury Stock Acquired, Average Cost Per Share	$74.88
Stock Repurchased During Period, Value	470,000,000
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased	0
Series C Preferred Stock
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Dividends Per Share, Declared	$1,313	$1,313
Preferred stock cash dividend	6,000,000	6,000,000
Series C Preferred Stock, Depository Share
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Dividends Per Share, Declared	$0.33	$0.33
Series D Preferred Stock
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Dividends Per Share, Declared	$1,475	$0
Preferred stock cash dividend	11,000,000
Series D Preferred Stock, Depository Share
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Dividends Per Share, Declared	$0.37
Series E Preferred Stock
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Dividends Per Share, Declared	$1,833	$0
Preferred stock cash dividend	14,000,000
Series E Preferred Stock, Depository Share
Equity, Class of Treasury Stock [Line Items]
Preferred Stock, Dividends Per Share, Declared	$0.46
Retained Earnings
Equity, Class of Treasury Stock [Line Items]
Preferred stock cash dividend	31,000,000	6,000,000
Common stock dividends	($124,000,000)	($112,000,000)

Accumulated_Other_Comprehensiv3

Accumulated Other Comprehensive Income - Schedule Of Accumulated Other Comprehensive (Loss) Income (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Stockholders' Equity Note [Abstract]
Net unrealized gains on cash flow hedges	$288	$276
Net unrealized gains (losses) on available-for-sale securities portfolio	472	273
Net unrealized gains (losses) related to reclassified available-for-sale securities	35	39
Net unrealized gains (losses) on available-for-sale securities	507	312
Net unrealized losses on available-for-sale securities designated in fair value hedges	-136	-121
Other-than-temporary impairment on available-for-sale securities related to factors other than credit	0	1
Net unrealized losses on hedges of net investments in non-U.S. subsidiaries	-14	-14
Other-than-temporary impairment on held-to-maturity securities related to factors other than credit	-25	-29
Net unrealized losses on retirement plans	-267	-272
Foreign currency translation	-1,359	-660
Total	($1,006)	($507)	$188	($95)

Accumulated_Other_Comprehensiv4

Accumulated Other Comprehensive Income - Accumulated Other Comprehensive Income by Component (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
AOCI net of tax, beginning balance	($507)	($95)
Other comprehensive income (loss) before reclassifications		286
Amounts reclassified out of AOCI		-3
Other comprehensive income (loss)	-499	283
AOCI net of tax, ending balance	-1,006	188
Accumulated Other Comprehensive Income (Loss)
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
AOCI net of tax, beginning balance	-507
Other comprehensive income (loss) before reclassifications	-504
Amounts reclassified out of AOCI	5
Other comprehensive income (loss)	-499
AOCI net of tax, ending balance	-1,006
Net Unrealized Gains (Losses) on Cash Flow Hedges
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
AOCI net of tax, beginning balance	276	161
Other comprehensive income (loss) before reclassifications	11	-8
Amounts reclassified out of AOCI	1	1
Other comprehensive income (loss)	12	-7
AOCI net of tax, ending balance	288	154
Net Unrealized Gains (Losses) on Available-for-Sale Securities
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
AOCI net of tax, beginning balance	192	-221
Other comprehensive income (loss) before reclassifications	179	258
Amounts reclassified out of AOCI	0	-9
Other comprehensive income (loss)	179	249
AOCI net of tax, ending balance	371	28
Net Unrealized Losses on Hedges of Net Investments in Non-U.S. Subsidiaries
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
AOCI net of tax, beginning balance	-14	-14
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified out of AOCI	0	0
Other comprehensive income (loss)	0	0
AOCI net of tax, ending balance	-14	-14
Other-Than-Temporary Impairment on Held-to-Maturity Securities
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
AOCI net of tax, beginning balance	-29	-47
Other comprehensive income (loss) before reclassifications	5	8
Amounts reclassified out of AOCI	-1	0
Other comprehensive income (loss)	4	8
AOCI net of tax, ending balance	-25	-39
Net Unrealized Losses on Retirement Plans
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
AOCI net of tax, beginning balance	-272	-203
Other comprehensive income (loss) before reclassifications	0	1
Amounts reclassified out of AOCI	5	5
Other comprehensive income (loss)	5	6
AOCI net of tax, ending balance	-267	-197
Foreign Currency Translation
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
AOCI net of tax, beginning balance	-660	229
Other comprehensive income (loss) before reclassifications	-699	27
Amounts reclassified out of AOCI	0	0
Other comprehensive income (loss)	-699	27
AOCI net of tax, ending balance	($1,359)	$256

Accumulated_Other_Comprehensiv5

Accumulated Other Comprehensive Income - Adjustments to Accumulated Other Comprehensive Income (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Class of Stock [Line Items]
Net interest revenue	$546	$555
Total reclassifications out of AOCI	377	356
Reclassification out of Accumulated Other Comprehensive Income
Class of Stock [Line Items]
Total reclassifications out of AOCI	5	-3
Net Unrealized Gains (Losses) on Cash Flow Hedges | Interest-rate contracts | Reclassification out of Accumulated Other Comprehensive Income
Class of Stock [Line Items]
Net interest revenue	1	1
Net Unrealized Gains (Losses) on Available-for-Sale Securities | Reclassification out of Accumulated Other Comprehensive Income
Class of Stock [Line Items]
Net gains (losses) from sales of available-for-sale securities	0	-9
Gain (Loss) on Investments, Excluding Other than Temporary Impairments, Tax	0	-6
Other-Than-Temporary Impairment on Held-to-Maturity Securities | Reclassification out of Accumulated Other Comprehensive Income
Class of Stock [Line Items]
Other-than-temporary impairment on held-to-maturity securities related to factors other than credit	-1	0
Net Unrealized Losses on Retirement Plans | Reclassification out of Accumulated Other Comprehensive Income
Class of Stock [Line Items]
Amortization of actuarial losses, net of related tax benefits of $3 and $3, respectively	5	5
OCI reclassification adjustment, pension and other postretirement benefit plans, tax	($4)	$3

Regulatory_Capital_Details

Regulatory Capital (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Retained earnings	$15,135	$14,882
Tier One Common Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%	4.00%
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%	5.50%
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%	8.00%
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Basel III Advanced Approaches
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus	10,248	10,295
Retained earnings	15,135	14,882
Accumulated other comprehensive income (loss)	-1,226	-641
Treasury Stock Value, Excluding Preferred Shares	-5,519	-5,158
Total shareholders’ equity	18,638	19,378
Goodwill and other intangible assets, net of associated deferred tax liabilities	-5,932	-5,869
Other adjustments, common tier calculation	-62	-36
Tier one common risk-based capital	12,644	13,473
Preferred stock	1,961	1,961
Trust preferred capital securities subject to phase-out from tier 1 capital	237	475
Other adjustments, tier 1 risk based calculation	-94	-145
Tier One Risk Based Capital	14,748	15,764
Total Capital Qualifying Subordinated Long-Term Debt	1,439	1,618
Trust preferred capital securities phased out of tier 1 capital	713	475
Other adjustments, total capital calculation	2	4
Capital	16,902	17,861
Risk-weighted assets - credit risk	63,820	66,874
Risk-weighted assets - operational risk	35,765	35,866
Risk-weighted assets - market risk	4,413	5,087
Total risk-weighted assets	103,998	107,827
Adjusted Quarterly Average Assets	252,406	247,740
Value-at-risk	12.20%	12.50%
Stressed value-at-risk	14.20%	14.60%
Correlation valuation adjustment	16.30%	16.60%
Tier One Leverage Capital to Average Assets	5.80%	6.40%
Basel III Standardized Approach
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus	10,248
Retained earnings	15,135
Accumulated other comprehensive income (loss)	-1,226
Treasury Stock Value, Excluding Preferred Shares	-5,519
Total shareholders’ equity	18,638
Goodwill and other intangible assets, net of associated deferred tax liabilities	-5,932
Other adjustments, common tier calculation	-62
Tier one common risk-based capital	12,644
Preferred stock	1,961
Trust preferred capital securities subject to phase-out from tier 1 capital	237
Other adjustments, tier 1 risk based calculation	-94
Tier One Risk Based Capital	14,748
Total Capital Qualifying Subordinated Long-Term Debt	1,439
Trust preferred capital securities phased out of tier 1 capital	713
Other adjustments, total capital calculation	2
Capital	16,902
Risk-weighted assets - credit risk	119,582
Risk-weighted assets - market risk	2,364
Total risk-weighted assets	121,946
Adjusted Quarterly Average Assets	252,406
Value-at-risk	10.40%
Stressed value-at-risk	12.10%
Correlation valuation adjustment	13.90%
Tier One Leverage Capital to Average Assets	5.80%
Basel III Transitional Approach
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus		10,295
Retained earnings		14,882
Accumulated other comprehensive income (loss)		-641
Treasury Stock Value, Excluding Preferred Shares		-5,158
Total shareholders’ equity		19,378
Goodwill and other intangible assets, net of associated deferred tax liabilities		-5,869
Other adjustments, common tier calculation		-36
Tier one common risk-based capital		13,473
Preferred stock		1,961
Trust preferred capital securities subject to phase-out from tier 1 capital		475
Other adjustments, tier 1 risk based calculation		-145
Tier One Risk Based Capital		15,764
Total Capital Qualifying Subordinated Long-Term Debt		1,618
Trust preferred capital securities phased out of tier 1 capital		475
Other adjustments, total capital calculation		4
Capital		17,861
Risk-weighted assets - credit risk		87,502
Risk-weighted assets - market risk		2,910
Total risk-weighted assets		90,412
Adjusted Quarterly Average Assets		247,740
Value-at-risk		14.90%
Stressed value-at-risk		17.40%
Correlation valuation adjustment		19.80%
Tier One Leverage Capital to Average Assets		6.40%
State Street Bank | Basel III Advanced Approaches
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus	10,901	10,867
Retained earnings	9,801	9,416
Accumulated other comprehensive income (loss)	-1,048	-535
Treasury Stock Value, Excluding Preferred Shares	0	0
Total shareholders’ equity	19,654	19,748
Goodwill and other intangible assets, net of associated deferred tax liabilities	-5,632	-5,577
Other adjustments, common tier calculation	-102	-128
Tier one common risk-based capital	13,920	14,043
Preferred stock	0	0
Trust preferred capital securities subject to phase-out from tier 1 capital	0	0
Other adjustments, tier 1 risk based calculation	0	0
Tier One Risk Based Capital	13,920	14,043
Total Capital Qualifying Subordinated Long-Term Debt	1,453	1,634
Trust preferred capital securities phased out of tier 1 capital	0	0
Other adjustments, total capital calculation	0	0
Capital	15,373	15,677
Risk-weighted assets - credit risk	56,527	59,836
Risk-weighted assets - operational risk	35,348	35,449
Risk-weighted assets - market risk	4,407	5,048
Total risk-weighted assets	96,282	100,333
Adjusted Quarterly Average Assets	248,022	243,549
Value-at-risk	14.50%	14.00%
Stressed value-at-risk	14.50%	14.00%
Correlation valuation adjustment	16.00%	15.60%
Tier One Leverage Capital to Average Assets	5.60%	5.80%
State Street Bank | Basel III Standardized Approach
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus	10,901
Retained earnings	9,801
Accumulated other comprehensive income (loss)	-1,048
Treasury Stock Value, Excluding Preferred Shares	0
Total shareholders’ equity	19,654
Goodwill and other intangible assets, net of associated deferred tax liabilities	-5,632
Other adjustments, common tier calculation	-102
Tier one common risk-based capital	13,920
Preferred stock	0
Trust preferred capital securities subject to phase-out from tier 1 capital	0
Other adjustments, tier 1 risk based calculation	0
Tier One Risk Based Capital	13,920
Total Capital Qualifying Subordinated Long-Term Debt	1,453
Trust preferred capital securities phased out of tier 1 capital	0
Other adjustments, total capital calculation	0
Capital	15,373
Risk-weighted assets - credit risk	112,454
Risk-weighted assets - market risk	2,363
Total risk-weighted assets	114,817
Adjusted Quarterly Average Assets	248,022
Value-at-risk	12.10%
Stressed value-at-risk	12.10%
Correlation valuation adjustment	13.40%
Tier One Leverage Capital to Average Assets	5.60%
State Street Bank | Basel III Transitional Approach
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common stock and related surplus		10,867
Retained earnings		9,416
Accumulated other comprehensive income (loss)		-535
Treasury Stock Value, Excluding Preferred Shares		0
Total shareholders’ equity		19,748
Goodwill and other intangible assets, net of associated deferred tax liabilities		-5,577
Other adjustments, common tier calculation		-128
Tier one common risk-based capital		14,043
Preferred stock		0
Trust preferred capital securities subject to phase-out from tier 1 capital		0
Other adjustments, tier 1 risk based calculation		0
Tier One Risk Based Capital		14,043
Total Capital Qualifying Subordinated Long-Term Debt		1,634
Trust preferred capital securities phased out of tier 1 capital		0
Other adjustments, total capital calculation		0
Capital		15,677
Risk-weighted assets - credit risk		84,433
Risk-weighted assets - market risk		2,909
Total risk-weighted assets		87,342
Adjusted Quarterly Average Assets		$243,549
Value-at-risk		16.10%
Stressed value-at-risk		16.10%
Correlation valuation adjustment		17.90%
Tier One Leverage Capital to Average Assets		5.80%

Derivative_Financial_Instrumen2

Derivative Financial Instruments - Narrative (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Derivative [Line Items]
Cash collateral received for derivative instruments	$1,490,000,000		$1,790,000,000
Cash collateral provided for derivative instruments	4,870,000,000		4,790,000,000
Fair value of derivative liabilities	17,397,000,000		15,234,000,000
Maximum additional amount of payments related to termination events	0
Securities weighted average life (in years)	5 years 8 months 15 days	5 years 10 months 18 days
OCI, change in gain (loss) of fair value hedge, net of tax	15,000,000	10,000,000
Fair Value Hedges | 1.35% Senior Note
Derivative [Line Items]
Fixed interest rate	1.35%
Fair Value Hedges | 3.70% notes due in 2023
Derivative [Line Items]
Fixed interest rate	3.70%
Fair Value Hedges | 3.30% notes due 2024
Derivative [Line Items]
Fixed interest rate	3.30%
Credit swap agreements
Derivative [Line Items]
Fair value of derivative liabilities	2,160,000,000
Maximum additional amount of payments related to termination events	$2,000,000,000
Interest rate swap | Fair Value Hedges | 3.1% Subordinated Note
Derivative [Line Items]
Fixed interest rate	3.10%
Interest rate swap | Fair Value Hedges | Senior notes
Derivative [Line Items]
Number of securities	3
Interest rate swap | Fair Value Hedges | Subordinated note
Derivative [Line Items]
Number of securities	1

Derivative_Financial_Instrumen3

Derivative Financial Instruments - Schedule of Outstanding Hedges: (Notional Amount) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Other contracts | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivatives	$417	$210
Swap agreements and forwards | Interest-rate contracts | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivatives	474	645
Futures | Interest-rate contracts | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivatives	2,969	3,939
Futures | Foreign exchange contracts | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivatives	21	0
Forward, swap and spot | Foreign exchange contracts | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivatives	1,414,506	1,231,344
Options purchased | Foreign exchange contracts | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivatives	3,008	2,767
Options written | Foreign exchange contracts | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivatives	2,905	2,404
Credit swap agreements | Credit derivative contracts | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivatives	226	191
Commodity(1) | Futures Contracts | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivatives	61	26
Equity(1) | Futures Contracts | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivatives	92	2
Stable value contracts | Other contracts | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivatives	23,425	23,409
Swap agreements | Interest-rate contracts | Derivatives designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivatives	6,065	6,077
Forward and swap | Foreign exchange contracts | Derivatives designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivatives	2,605	2,705
Long | Options and caps purchased | Interest-rate contracts | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivatives	4	7
Short | Options and caps purchased | Interest-rate contracts | Derivatives not designated as hedging instruments
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivatives	$4	$7

Derivative_Financial_Instrumen4

Derivative Financial Instruments - Notional Amount of Interest Rate Swap Agreements Designated as Fair Value and Cash Flow Hedges (Details) (USD $)	3 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Increase (decrease) in carrying value of long-term debt	($135)	$76
Fair Value Hedges
Derivative [Line Items]
Total	6,065	6,077
Fair Value Hedges | Investment securities available for sale
Derivative [Line Items]
Investment securities available for sale	2,565	2,577
Fair Value Hedges | Long-term debt
Derivative [Line Items]
Long-term debt	$3,500	$3,500

Derivative_Financial_Instrumen5

Derivative Financial Instruments - Contractual and Weighted-Average Interest Rates, Which Include the Effects of Hedges Related to Financial Instruments (Details) (Long-term debt)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Long-term debt
Derivative [Line Items]
Contractual Rates	3.53%	3.39%
Rate Including Impact of Hedges	2.54%	2.60%

Derivative_Financial_Instrumen6

Derivative Financial Instruments - Schedule of The Fair Values of Derivative Financial Instruments (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	$16,260	$15,214
Fair value of derivative liabilities	17,397	15,234
Foreign exchange contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	16,116	15,135
Fair value of derivative liabilities	17,053	14,925
Interest-rate contracts
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	141	77
Fair value of derivative liabilities	232	239
Derivatives not designated as hedging instruments | Other assets
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	15,625	14,643
Derivatives not designated as hedging instruments | Other liabilities
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	17,177	15,008
Derivatives not designated as hedging instruments | Foreign exchange contracts | Other assets
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	15,610	14,626
Derivatives not designated as hedging instruments | Foreign exchange contracts | Other liabilities
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	17,053	14,922
Derivatives not designated as hedging instruments | Interest-rate contracts | Other assets
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	12	15
Derivatives not designated as hedging instruments | Interest-rate contracts | Other liabilities
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	12	16
Derivatives not designated as hedging instruments | Other derivative contracts | Other assets
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	3	2
Derivatives not designated as hedging instruments | Other derivative contracts | Other liabilities
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	112	70
Derivatives designated as hedging instruments | Other assets
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	635	571
Derivatives designated as hedging instruments | Other liabilities
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	220	226
Derivatives designated as hedging instruments | Foreign exchange contracts | Other assets
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	506	509
Derivatives designated as hedging instruments | Foreign exchange contracts | Other liabilities
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	0	3
Derivatives designated as hedging instruments | Interest-rate contracts | Other assets
Derivatives, Fair Value [Line Items]
Fair value of derivative assets	129	62
Derivatives designated as hedging instruments | Interest-rate contracts | Other liabilities
Derivatives, Fair Value [Line Items]
Fair value of derivative liabilities	$220	$223

Derivative_Financial_Instrumen7

Derivative Financial Instruments - Impact of Derivatives on Consolidated Statement of Income (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Derivatives not designated as hedging instruments
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	$207	$133
Compensation and Employee Benefits | Derivatives not designated as hedging instruments
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	59	49
Foreign exchange contracts | Trading services | Derivatives not designated as hedging instruments
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	204	134
Interest-rate contracts | Processing fees and other revenue | Derivatives not designated as hedging instruments
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	1	0
Other derivative contracts | Trading services | Derivatives not designated as hedging instruments
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	2	-1
Other derivative contracts | Compensation and Employee Benefits | Derivatives not designated as hedging instruments
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	59	49
Fair Value Hedges
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	-24	79
Amount of Gain (Loss) on Hedged Item Recognized in Consolidated Statement of Income	27	-75
Fair Value Hedges | Foreign exchange contracts | Processing fees and other revenue
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	-67	42
Fair Value Hedges | Foreign exchange contracts | Processing fees and other revenue | Investment securities
Derivative [Line Items]
Amount of Gain (Loss) on Hedged Item Recognized in Consolidated Statement of Income	67	-42
Fair Value Hedges | Interest-rate contracts | Processing fees and other revenue | Contract one
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	-25	-12
Fair Value Hedges | Interest-rate contracts | Processing fees and other revenue | Contract two
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	68	49
Fair Value Hedges | Interest-rate contracts | Processing fees and other revenue | Long-term debt
Derivative [Line Items]
Amount of Gain (Loss) on Hedged Item Recognized in Consolidated Statement of Income	25	12
Fair Value Hedges | Interest-rate contracts | Processing fees and other revenue | Investment securities available for sale
Derivative [Line Items]
Amount of Gain (Loss) on Hedged Item Recognized in Consolidated Statement of Income	($65)	($45)

Derivative_Financial_Instrumen8

Derivative Financial Instruments - Schedule of Differences Between the Gains (Losses) on the Derivative and The Gains (Losses) on the Hedged Item (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Derivative [Line Items]
Amount of Gain (Loss) Reclassified from OCI to Consolidated Statement of Income	$2,605	$2,485
Cash Flow Hedges
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Other Comprehensive Income	20	-13
Amount of Gain (Loss) Reclassified from OCI to Consolidated Statement of Income	-1	-1
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	2	2
Interest-rate contracts | Net interest revenue | Cash Flow Hedges
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Other Comprehensive Income	0	-1
Amount of Gain (Loss) Reclassified from OCI to Consolidated Statement of Income	-1	-1
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	0	1
Foreign exchange contracts | Net interest revenue | Cash Flow Hedges
Derivative [Line Items]
Amount of Gain (Loss) on Derivative Recognized in Other Comprehensive Income	20	-12
Amount of Gain (Loss) Reclassified from OCI to Consolidated Statement of Income	0	0
Amount of Gain (Loss) on Derivative Recognized in Consolidated Statement of Income	$2	$1

Offsetting_Arrangements_Narrat

Offsetting Arrangements - Narrative (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Offsetting [Abstract]
Fair Value of Securities Received as Collateral that Can be Resold or Repledged	$11,480,000,000	$2,600,000,000
Fair Value of Securities Received as Collateral that Have Been Resold or Repledged	$186,000,000	$125,000,000

Offsetting_Arrangements_Assets

Offsetting Arrangements - Assets With Offsetting Arrangements (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	$16,260	$15,214
Derivatives, Gross Amounts Offset in Statement of Condition	-8,212	-7,280
Net Amounts of Assets Presented in Statement of Condition	8,048	7,934
Derivative, Collateral, Cash Offset	-466	-983
Total Net Derivative Asset	8,048	7,934
Resale Agreements and Securities Borrowing, Gross Amounts of Recognized Assets	62,587	47,488
Resale Agreements and Securities Borrowing, Gross Amounts Offset in Statement of Condition	-31,407	-29,157
Net Amounts of Assets Presented in Statement of Condition	31,180	18,331
Total, Gross Amounts of Recognized Assets	78,847	62,702
Total, Gross Amounts Offset in Statement of Condition	-39,619	-36,437
Total, Net Amounts of Assets Presented in Statement of Condition	39,228	26,265
Securities purchased under resale agreements	11,331	2,390
Securities borrowed subject to master netting arrangements	19,849	15,941
Foreign exchange contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	16,116	15,135
Derivatives, Gross Amounts Offset in Statement of Condition	-7,730	-6,275
Net Amounts of Assets Presented in Statement of Condition	8,386	8,860
Interest-rate contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	141	77
Derivatives, Gross Amounts Offset in Statement of Condition	-14	-21
Net Amounts of Assets Presented in Statement of Condition	127	56
Other derivative contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	3	2
Derivatives, Gross Amounts Offset in Statement of Condition	-2	-1
Net Amounts of Assets Presented in Statement of Condition	$1	$1

Offsetting_Arrangements_Assets1

Offsetting Arrangements - Assets With Enforceable Netting Arrangements (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Offsetting [Abstract]
Derivative, Net Amount of Assets Presented in Statement of Condition	$8,048	$7,934
Derivatives, Counterparty Netting	0	0
Derivatives, Collateral Received	-1,442	-1,490
Derivatives, Net Amount	6,606	6,444
Resale Agreements and Securities Borrowing, Resale Agreements and Securities Borrowing, Net Amount of Assets Presented in Statement of Condition	31,180	18,331
Resale Agreements and Securities Borrowing, Counterparty Netting	-283	-128
Resale Agreements and Securities Borrowing, Collateral Received	-30,842	-18,157
Resale Agreements and Securities Borrowing, Net Amount	55	46
Total, Net Amounts of Assets Presented in Statement of Condition	39,228	26,265
Total, Counterparty Netting	-283	-128
Total, Collateral Received	-32,284	-19,647
Total, Net Amount	$6,661	$6,490

Offsetting_Arrangements_Liabil

Offsetting Arrangements - Liabilities With Offsetting Arrangements (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	$17,397	$15,234
Gross Amounts Offset in Statement of Condition	-10,407	-8,926
Net Amounts of Liabilities Presented in Statement of Condition	6,990	6,308
Derivative Collateral, Cash Offset	-2,661	-2,630
Total Net Derivative Liability	6,990	6,308
Gross Amounts of Recognized Liabilities	48,718	44,562
Gross Amounts Offset in Statement of Condition	-31,407	-29,157
Net Amounts of Liabilities Presented in Statement of Condition	17,311	15,405
Gross Amounts of Recognized Liabilities	66,115	59,796
Gross Amounts Offset in Statement of Condition	-41,814	-38,083
Total, Net Amount of Liabilities Presented in Statement of Condition	24,301	21,713
Securities sold under repurchase agreements	10,158	8,925
Securities Lending, Fair Value, Amount Not Offset Against Collateral	7,153	6,480
Foreign exchange contracts
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	17,053	14,925
Gross Amounts Offset in Statement of Condition	-7,730	-6,275
Net Amounts of Liabilities Presented in Statement of Condition	9,323	8,650
Interest-rate contracts
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	232	239
Gross Amounts Offset in Statement of Condition	-14	-20
Net Amounts of Liabilities Presented in Statement of Condition	218	219
Other derivative contracts
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Liabilities	112	70
Gross Amounts Offset in Statement of Condition	-2	-1
Net Amounts of Liabilities Presented in Statement of Condition	$110	$69

Offsetting_Arrangements_Liabil1

Offsetting Arrangements - Liabilities With Enforceable Netting Arrangements (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Offsetting [Abstract]
Derivative, Net Amount of Liabilities Presented in Statement of Condition	$6,990	$6,308
Derivative, Counterparty Netting	0	0
Derivative, Collateral Provided	-110	-19
Derivative, Net Amount	6,880	6,289
Repurchase Agreements and Securities Lending, Net Amount of Liabilities Presented in Statement of Condition	17,311	15,405
Repurchase Agreements and Securities Lending, Counterparty Netting	-283	-128
Repurchase Agreements and Securities Lending, Collateral Provided	-15,274	-13,872
Repurchase Agreements and Securities Lending, Net Amount	1,754	1,405
Total, Net Amount of Liabilities Presented in Statement of Condition	24,301	21,713
Total, Counterparty Netting	-283	-128
Total, Collateral Provided	-15,384	-13,891
Total, Net Amount	$8,634	$7,694

Net_Interest_Revenue_Component

Net Interest Revenue - Components of Interest Revenue and Interest Expenses (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Net Interest Revenue [Abstract]
Deposits with banks	$54	$34
U.S. Treasury and federal agencies	183	163
State and political subdivisions	58	71
Other investments	259	319
Securities purchased under resale agreements	11	9
Loans and leases	74	58
Other interest-earning assets	3	1
Total interest revenue	642	655
Deposits	26	15
Short-term borrowings	1	15
Long-term debt	62	63
Other interest-bearing liabilities	7	7
Total interest expense	96	100
Net interest revenue	$546	$555

Expenses_Narrative_Details

Expenses - Narrative (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Other Expenses [Abstract]
Restructuring charges, net	$1	$12

Expenses_Costs_Related_To_Acqu

Expenses - Costs Related To Acquisition And Restructuring (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Other Expenses [Abstract]
Acquisition costs	$5	$21
Restructuring charges, net	1	12
Total acquisition and restructuring costs	$6	$33

Expenses_Activity_Related_To_R

Expenses - Activity Related To Restructuring-Related Accruals (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Restructuring Reserve [Roll Forward]
Balance as of December 31, 2014	$71
Additional accruals for Business Operations and Information Technology Transformation program	-3
Payments and adjustments	-18
Balance as of March 31, 2015	54
2012 Expense Control Measures
Restructuring Reserve [Roll Forward]
Additional accruals for 2012 expense control measures	4
Employee- Related Costs
Restructuring Reserve [Roll Forward]
Balance as of December 31, 2014	40
Additional accruals for Business Operations and Information Technology Transformation program	-3
Payments and adjustments	-10
Balance as of March 31, 2015	27
Employee- Related Costs | 2012 Expense Control Measures
Restructuring Reserve [Roll Forward]
Additional accruals for 2012 expense control measures	0
Real Estate Consolidation
Restructuring Reserve [Roll Forward]
Balance as of December 31, 2014	24
Additional accruals for Business Operations and Information Technology Transformation program	0
Payments and adjustments	-3
Balance as of March 31, 2015	21
Real Estate Consolidation | 2012 Expense Control Measures
Restructuring Reserve [Roll Forward]
Additional accruals for 2012 expense control measures	0
Asset and Other Write-Offs
Restructuring Reserve [Roll Forward]
Balance as of December 31, 2014	7
Additional accruals for Business Operations and Information Technology Transformation program	0
Payments and adjustments	-5
Balance as of March 31, 2015	6
Asset and Other Write-Offs | 2012 Expense Control Measures
Restructuring Reserve [Roll Forward]
Additional accruals for 2012 expense control measures	$4

Earnings_Per_Common_Share_Comp

Earnings Per Common Share - Computation of Basic and Diluted Earnings Per Share (Details) (USD $)	3 Months Ended
In Millions, except Share data in Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Earnings Per Share [Abstract]
Net income	$409	$363
Preferred stock dividends	-31	-6
Dividends and undistributed earnings allocated to participating securities(1)	-1	-1
Net income available to common shareholders	$377	$356
Basic (in shares)	412,225	430,621
Effect of dilutive securities: common stock options and common stock awards	6,525	8,194
Diluted average common shares	418,750	438,815
Anti-dilutive securities (in shares)	791	1,504
Earnings per Common Share:
Basic (in dollars per share)	$0.91	$0.83
Diluted (in dollars per share)	$0.90	$0.81

Line_of_Business_Information_S

Line of Business Information - Summary of Line of Business (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information [Line Items]
Servicing fees	$1,273	$1,238
Management fees	301	292
Trading services	324	253
Securities finance	101	85
Processing fees and other	61	56
Total fee revenue	2,060	1,924
Net interest revenue	546	555
Gains (losses) related to investment securities, net	-1	6
Total revenue	2,605	2,485
Provision for loan losses	4	2
Total expenses	2,097	2,028
Income before income tax expense	504	455
Pre-tax margin	19.00%	18.00%
Investment Servicing
Segment Reporting Information [Line Items]
Servicing fees	1,273	1,238
Management fees	0	0
Trading services	315	241
Securities finance	101	85
Processing fees and other	59	55
Total fee revenue	1,748	1,619
Net interest revenue	545	551
Gains (losses) related to investment securities, net	-1	6
Total revenue	2,292	2,176
Provision for loan losses	4	2
Total expenses	1,836	1,672
Income before income tax expense	452	502
Pre-tax margin	20.00%	23.00%
Investment Management
Segment Reporting Information [Line Items]
Servicing fees	0	0
Management fees	301	292
Trading services	9	12
Securities finance	0	0
Processing fees and other	2	1
Total fee revenue	312	305
Net interest revenue	1	4
Gains (losses) related to investment securities, net	0	0
Total revenue	313	309
Provision for loan losses	0	0
Total expenses	256	245
Income before income tax expense	57	64
Pre-tax margin	18.00%	21.00%
Other
Segment Reporting Information [Line Items]
Servicing fees	0	0
Management fees	0	0
Trading services	0	0
Securities finance	0	0
Processing fees and other	0	0
Total fee revenue	0	0
Net interest revenue	0	0
Gains (losses) related to investment securities, net	0	0
Total revenue	0	0
Provision for loan losses	0	0
Total expenses	5	111
Income before income tax expense	($5)	($111)

Line_of_Business_Information_N

Line of Business Information - Narrative (Details)	3 Months Ended
	Mar. 31, 2015
	line_of_business
Segment Reporting [Abstract]
Number of lines of business	2

NonUS_Activities_Schedule_Of_R

Non-U.S. Activities - Schedule Of Results From Non-U.S. Operations (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information [Line Items]
Total fee revenue	$2,060	$1,924
Net interest revenue	546	555
Gains (losses) related to investment securities, net	-1	6
Total revenue	2,605	2,485
Expenses	2,097	2,028
Income before income tax expense	504	455
Income tax expense	95	92
Net income	409	363
Non- U.S.
Segment Reporting Information [Line Items]
Total fee revenue	857	788
Net interest revenue	291	312
Gains (losses) related to investment securities, net	-1	6
Total revenue	1,147	1,106
Expenses	805	852
Income before income tax expense	342	254
Income tax expense	78	61
Net income	$264	$193

NonUS_Activities_Summary_Of_No

Non-U.S. Activities - Summary Of Non-U.S. Assets (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Segment Reporting Information [Line Items]
Interest-bearing deposits with banks	$83,398	$93,523
Other assets	37,549	32,600
Total assets	279,476	274,119
Non- U.S.
Segment Reporting Information [Line Items]
Interest-bearing deposits with banks	26,893	17,382
Investment securities	26,863	29,060
Other assets	13,948	13,577
Total assets	$67,704	$60,019