Change In Unrealized Gains Losses Related To Financial Instruments

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Namespace Prefix:	stt
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- Definition

This element represents total gains or losses for the period (realized and unrealized), arising from assets measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in earnings or resulted in a change in net asset value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph c(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258

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- Definition

This element represents total gains or losses for the period (realized and unrealized), arising from assets measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in other comprehensive income (a separate component of shareholders' equity).

+ References

+ Details

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- Definition

Purchases that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(2)

-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This element represents purchases, sales, issuances, and settlements (net) which have taken place during the period in relation to assets measured at fair value on a recurring basis using unobservable inputs (Level 3).

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Sales that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.

+ References

+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

Settlements that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy.

+ References

+ Details

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Period Type:	duration

- Definition

Transfers into assets measured at fair value and categorized within Level 3 of the fair value hierarchy that have taken place during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(3)

-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258

+ Details

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Period Type:	duration

- Definition

This element represents [net] transfers in to and out of assets measured at fair value on a recurring basis using unobservable inputs (Level 3) which have taken place during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph c(3)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(3)

-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258

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- Definition

Transfers out of assets measured at fair value and categorized within Level 3 of the fair value hierarchy that have taken place during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(3)

-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258

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- Definition

This element represents an asset measured at fair value using significant unobservable inputs (Level 3) which is required for reconciliation purposes of beginning and ending balances.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6925170&loc=d3e19207-110258

+ Details

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- Definition

This element represents total gains or losses for the period (realized and unrealized), arising from liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3), which are included in earnings or resulted in a change in net asset value.

+ References

+ Details

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Period Type:	duration

- Definition

Issues that have taken place during the period in relation to liabilities measured at fair value and categorized within Level 3 of the fair value hierarchy.

+ References

+ Details

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- Definition

Purchases that have taken place during the period in relation to liabilities measured at fair value and categorized within Level 3 of the fair value hierarchy.

+ References

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

This element represents purchases, sales, issuances, and settlements (net) which have taken place during the period in relation to liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3).

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Sales that have taken place during the period in relation to liabilities measured at fair value and categorized within Level 3 of the fair value hierarchy.

+ References

+ Details

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Balance Type:	debit
Period Type:	duration

- Definition

Settlements that have taken place during the period in relation to liabilities measured at fair value and categorized within Level 3 of the fair value hierarchy.

+ References

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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- Definition

This element represents the aggregate of the liabilities reported on the balance sheet at period end measured at fair value by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

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Fair Value (Schedule Of Fair Value Measurements Using Significant Unobservable Inputs) (Details) (USD $) In Millions	3 Months Ended	9 Months Ended	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended							3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended				3 Months Ended	9 Months Ended	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended				3 Months Ended		9 Months Ended
	Sep. 30, 2011 Direct Obligations [Member]	Sep. 30, 2011 Direct Obligations [Member]	Sep. 30, 2011 Mortgage-Backed Securities [Member]	Sep. 30, 2010 Mortgage-Backed Securities [Member]	Sep. 30, 2011 Mortgage-Backed Securities [Member]	Sep. 30, 2010 Mortgage-Backed Securities [Member]	Sep. 30, 2011 Student Loans [Member]	Sep. 30, 2010 Student Loans [Member]	Sep. 30, 2011 Student Loans [Member]	Sep. 30, 2010 Student Loans [Member]	Sep. 30, 2011 Credit Cards [Member]	Sep. 30, 2010 Credit Cards [Member]	Sep. 30, 2011 Credit Cards [Member]	Sep. 30, 2010 Credit Cards [Member]	Sep. 30, 2010 Sub-Prime [Member]	Sep. 30, 2010 Sub-Prime [Member]	Sep. 30, 2011 Other Asset-Backed Securities [Member]	Sep. 30, 2010 Other Asset-Backed Securities [Member]	Sep. 30, 2011 Other Asset-Backed Securities [Member]	Sep. 30, 2010 Other Asset-Backed Securities [Member]	Sep. 30, 2011 Total Asset-Backed Securities [Member]	Sep. 30, 2010 Total Asset-Backed Securities [Member]	Sep. 30, 2011 Total Asset-Backed Securities [Member]	Sep. 30, 2010 Total Asset-Backed Securities [Member]	Sep. 30, 2011 Non-U.S. Debt Securities [Member]	Sep. 30, 2010 Non-U.S. Debt Securities [Member]	Sep. 30, 2011 Non-U.S. Debt Securities [Member]	Sep. 30, 2010 Non-U.S. Debt Securities [Member]	Sep. 30, 2011 State And Political Subdivisions [Member]	Sep. 30, 2010 State And Political Subdivisions [Member]	Sep. 30, 2011 State And Political Subdivisions [Member]	Sep. 30, 2010 State And Political Subdivisions [Member]	Sep. 30, 2011 Collateralized Mortgage Obligations [Member]	Sep. 30, 2010 Collateralized Mortgage Obligations [Member]	Sep. 30, 2011 Collateralized Mortgage Obligations [Member]	Sep. 30, 2010 Collateralized Mortgage Obligations [Member]	Sep. 30, 2011 Other U.S. Debt Securities [Member]	Jun. 30, 2011 Other U.S. Debt Securities [Member]	Sep. 30, 2010 Other U.S. Debt Securities [Member]	Jun. 30, 2010 Other U.S. Debt Securities [Member]	Dec. 31, 2009 Other U.S. Debt Securities [Member]	Sep. 30, 2011 Investment Securities Available For Sale [Member]	Sep. 30, 2010 Investment Securities Available For Sale [Member]	Sep. 30, 2011 Investment Securities Available For Sale [Member]	Sep. 30, 2010 Investment Securities Available For Sale [Member]	Sep. 30, 2011 Foreign Exchange Contracts [Member]	Sep. 30, 2010 Foreign Exchange Contracts [Member]	Sep. 30, 2011 Foreign Exchange Contracts [Member]	Sep. 30, 2010 Foreign Exchange Contracts [Member]	Sep. 30, 2011 Foreign Exchange Contracts [Member] Accrued Expenses And Other Liabilities [Member]	Sep. 30, 2010 Foreign Exchange Contracts [Member] Accrued Expenses And Other Liabilities [Member]	Sep. 30, 2011 Foreign Exchange Contracts [Member] Accrued Expenses And Other Liabilities [Member]	Sep. 30, 2010 Foreign Exchange Contracts [Member] Accrued Expenses And Other Liabilities [Member]	Sep. 30, 2011 Interest-Rate Contracts [Member]	Sep. 30, 2011 Interest-Rate Contracts [Member]	Sep. 30, 2011 Interest-Rate Contracts [Member] Accrued Expenses And Other Liabilities [Member]	Sep. 30, 2011 Interest-Rate Contracts [Member] Accrued Expenses And Other Liabilities [Member]	Sep. 30, 2010 Interest-Rate Contracts [Member] Accrued Expenses And Other Liabilities [Member]	Jun. 30, 2010 Interest-Rate Contracts [Member] Accrued Expenses And Other Liabilities [Member]	Dec. 31, 2009 Interest-Rate Contracts [Member] Accrued Expenses And Other Liabilities [Member]	Sep. 30, 2011 Total Derivative Instruments [Member]	Sep. 30, 2011 Total Derivative Instruments [Member]	Sep. 30, 2011 Total Derivative Instruments [Member] Accrued Expenses And Other Liabilities [Member]	Sep. 30, 2010 Total Derivative Instruments [Member] Accrued Expenses And Other Liabilities [Member]	Sep. 30, 2011 Total Derivative Instruments [Member] Accrued Expenses And Other Liabilities [Member]	Sep. 30, 2010 Total Derivative Instruments [Member] Accrued Expenses And Other Liabilities [Member]	Sep. 30, 2011 Total Assets Carried at Fair Value [Member]	Sep. 30, 2010 Total Assets Carried at Fair Value [Member]	Sep. 30, 2011 Total Assets Carried at Fair Value [Member]	Sep. 30, 2010 Total Assets Carried at Fair Value [Member]	Sep. 30, 2011 Accrued Expenses And Other Liabilities [Member]	Jun. 30, 2011 Accrued Expenses And Other Liabilities [Member]	Sep. 30, 2011 Total Liabilities Carried At Fair Value [Member]	Sep. 30, 2010 Total Liabilities Carried At Fair Value [Member]	Sep. 30, 2011 Total Liabilities Carried At Fair Value [Member]	Sep. 30, 2010 Total Liabilities Carried At Fair Value [Member]
Fair Value, beginning balance, Assets	$ 17		$ 932	$ 43	$ 673	$ 58	$ 1,289	$ 2,229	$ 1,234	$ 3,111	$ 79	$ 91	$ 43	$ 312	$ 4	$ 3	$ 2,530	$ 1,069	$ 2,000	$ 1,134	$ 3,898	$ 3,393	$ 3,277	$ 4,560	$ 2,116	$ 2,659	$ 1,145	$ 2,606	$ 54	$ 3	$ 50	$ 2	$ 173	$ 424	$ 359	$ 199	$ 3	$ 2	$ 3	$ 3	$ 3	$ 7,192	$ 6,525	$ 5,507	$ 7,428	$ 201	$ 307	$ 254	$ 128					$ 8							$ 209	$ 254					$ 7,401	$ 6,832	$ 5,761	$ 7,556
Fair Value, beginning balance, Liabilities																																																		203	275	260	138			25	9	9	9	9			228	284	269	147						11	239	284	269	147
Transfers into Level 3, Assets																			114				114								1													115																									115
Transfers out of Level 3, Assets	(17)	(17)			(404)		(379)		(720)		(20)		(35)						(135)		(399)		(890)		(609)		(1,432)		(2)		(3)		(31)		(359)							(1,058)		(3,105)																							(1,058)		(3,105)
Recorded in Revenue, Assets						(1)	(1)	3	2	8	2	1	3	15		1	5	(2)	22	37	6	2	27	61		28	1	103					31		363	(208)						37	30	391	(45)	54	(55)	(15)	(19)						5						54	(10)					91	(25)	381	(64)
Recorded in Revenue, Liabilities																																																		42	(51)	(21)	(55)				10						42	(51)	(11)	(55)							42	(51)	(11)	(55)
Recorded in Other Comprehensive Income, Assets			2		3	(1)	(6)	5	(6)	76			(2)	(15)			(34)	2	14	45	(40)	7	6	106	(4)	(10)	8	138	(1)				(1)	2	(2)	5						(44)	(1)	15	248																						(44)	(1)	15	248
Purchases, Assets	22	39	590		1,289				421		250		301				267		837		517		1,559		894		2,799				3		216		381							2,239		6,070		173		256						4	10						177	266					2,416		6,336
Purchases, Liabilities																																																								(1)	(5)						(1)		(5)								(1)		(5)
Issuances, Liabilities																																																		170		247				15	29						185		276						11		185		287
Sales, Assets																	(37)		(37)		(37)		(37)		(3)		(3)															(40)		(40)										(1)	(4)						(1)	(4)					(41)		(44)
Sales, Liabilities																																																								(16)	(20)						(16)		(20)								(16)		(20)
Settlements, Assets			(25)		(62)		46		18				1				2		(82)		48		(63)		(52)		(176)						(38)		(392)		(1)					(67)		(694)		(117)		(184)													(117)	(184)					(184)		(878)
Settlements, Liabilities																																																		(117)		(188)											(117)		(188)								(117)		(188)
Purchases, Issuances and Settlements, Net, Assets						(13)		17		(19)		(52)		(33)				(56)		(102)		(91)		(154)		1,175		1,122						80		510							1,164		1,465		127		270																			1,291		1,735
Purchases, Issuances and Settlements, Net, Liabilities																																																			129		270											129		270								129		270
Transfers Into and/or Out of Level 3, Assets				(42)		(42)		(659)		(1,581)				(239)	(4)	(4)		(141)		(242)		(804)		(2,066)		(459)		(576)		1		2											(1,304)		(2,682)																							(1,304)		(2,682)
Fair Value, ending balance, Assets	22	22	1,499	1	1,499	1	949	1,595	949	1,595	311	40	311	40			2,733	872	2,733	872	3,993	2,507	3,993	2,507	2,342	3,393	2,342	3,393	51	4	51	4	350	506	350	506	2	2	3	3	3	8,259	6,414	8,259	6,414	311	379	311	379					11	11						322	322					8,581	6,793	8,581	6,793
Fair Value, ending balance, Liabilities																																																		298	353	298	353			23	23	9	9	9			321	362	321	362					11	11	332	362	332	362
Change in Unrealized Gains (Losses) Related to Financial Instruments																																														$ 59	$ (13)	$ 40	$ (17)	$ 51	$ (22)	$ 32	$ (35)	$ 2	$ 9	$ 10	$ 10				$ 61	$ 49	$ 61	$ (22)	$ 42	$ (35)	$ 61	$ (13)	$ 49	$ (17)			$ 61	$ (22)	$ 42	$ (35)