Investment Securities - Schedule of Gross Pre-Tax Unrealized Losses on Investment Securities (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	$ 18,678	$ 6,383
Available for sale, gross unrealized losses less than 12 months	136	16
Available for sale, fair value 12 months or longer	10,412	22,572
Available for sale, gross unrealized losses 12 months or longer	147	520
Available for sale, fair value total	29,090	28,955
Available for sale, gross unrealized losses total	283	536
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	8,113	333
Available for sale, gross unrealized losses less than 12 months	25	2
Available for sale, fair value 12 months or longer	2,435	5,416
Available for sale, gross unrealized losses 12 months or longer	27	163
Available for sale, fair value total	10,548	5,749
Available for sale, gross unrealized losses total	52	165
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	3,742	961
Available for sale, gross unrealized losses less than 12 months	59	6
Available for sale, fair value 12 months or longer	4,360	6,512
Available for sale, gross unrealized losses 12 months or longer	95	158
Available for sale, fair value total	8,102	7,473
Available for sale, gross unrealized losses total	154	164
Total U.S. Treasury and federal agencies
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	11,855	1,294
Available for sale, gross unrealized losses less than 12 months	84	8
Available for sale, fair value 12 months or longer	6,795	11,928
Available for sale, gross unrealized losses 12 months or longer	122	321
Available for sale, fair value total	18,650	13,222
Available for sale, gross unrealized losses total	206	329
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	730	424
Available for sale, gross unrealized losses less than 12 months	1	1
Available for sale, fair value 12 months or longer	225	719
Available for sale, gross unrealized losses 12 months or longer	0	6
Available for sale, fair value total	955	1,143
Available for sale, gross unrealized losses total	1	7
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	387	358
Available for sale, gross unrealized losses less than 12 months	0	0
Available for sale, fair value 12 months or longer	506	1,052
Available for sale, gross unrealized losses 12 months or longer	2	13
Available for sale, fair value total	893	1,410
Available for sale, gross unrealized losses total	2	13
Non-U.S. sovereign, supranational and non-U.S. agency
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	4,695	3,972
Available for sale, gross unrealized losses less than 12 months	49	7
Available for sale, fair value 12 months or longer	2,695	5,788
Available for sale, gross unrealized losses 12 months or longer	20	125
Available for sale, fair value total	7,390	9,760
Available for sale, gross unrealized losses total	69	132
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	312	50
Available for sale, gross unrealized losses less than 12 months	2	0
Available for sale, fair value 12 months or longer	116	893
Available for sale, gross unrealized losses 12 months or longer	2	37
Available for sale, fair value total	428	943
Available for sale, gross unrealized losses total	4	37
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	6,124	4,804
Available for sale, gross unrealized losses less than 12 months	52	8
Available for sale, fair value 12 months or longer	3,542	8,452
Available for sale, gross unrealized losses 12 months or longer	24	181
Available for sale, fair value total	9,666	13,256
Available for sale, gross unrealized losses total	76	189
Asset-backed securities, student loans
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	12
Available for sale, gross unrealized losses less than 12 months	0
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	12
Available for sale, gross unrealized losses total	0
Asset-backed securities, collateralized loan obligations
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	684	183
Available for sale, gross unrealized losses less than 12 months	0	0
Available for sale, fair value 12 months or longer	0	1,605
Available for sale, gross unrealized losses 12 months or longer	0	6
Available for sale, fair value total	684	1,788
Available for sale, gross unrealized losses total	0	6
Asset-backed securities, non-agency CMBS and RMBS
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months		35
Available for sale, gross unrealized losses less than 12 months		0
Available for sale, fair value 12 months or longer		180
Available for sale, gross unrealized losses 12 months or longer		3
Available for sale, fair value total		215
Available for sale, gross unrealized losses total		3
Total asset-backed securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	696	218
Available for sale, gross unrealized losses less than 12 months	0	0
Available for sale, fair value 12 months or longer	0	1,785
Available for sale, gross unrealized losses 12 months or longer	0	9
Available for sale, fair value total	696	2,003
Available for sale, gross unrealized losses total	0	9
State and political subdivisions
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	0	64
Available for sale, gross unrealized losses less than 12 months	0	0
Available for sale, fair value 12 months or longer	26	104
Available for sale, gross unrealized losses 12 months or longer	0	1
Available for sale, fair value total	26	168
Available for sale, gross unrealized losses total	0	1
Other U.S. debt securities
Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]
Available for sale, fair value less than 12 months	3	3
Available for sale, gross unrealized losses less than 12 months	0	0
Available for sale, fair value 12 months or longer	49	303
Available for sale, gross unrealized losses 12 months or longer	1	8
Available for sale, fair value total	52	306
Available for sale, gross unrealized losses total	$ 1	$ 8

Gross Pre-Tax Unrealized Losses On Investment Securities [Line Items]

No definition available.

Name:	stt_GrossPreTaxUnrealizedLossesOnInvestmentSecuritiesLineItems
Namespace Prefix:	stt_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 55
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479081/326-30-55-8

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-7

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479106/326-30-50-5

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479106/326-30-50-5

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 55
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479081/326-30-55-8

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-6

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479106/326-30-50-4

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-6

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479106/326-30-50-4

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FinancialInstrumentAxis=stt_UsTreasuryAndFederalAgenciesDirectObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=stt_UsTreasuryAndFederalAgenciesMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USTreasuryAndGovernmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=stt_NonUsDebtSecuritiesMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=stt_NonUsDebtSecuritiesAssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=stt_NonUSDebtSecuritiesForeignSovereignSupranationalAndNonAgencySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=stt_NonUsDebtSecuritiesOtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=stt_NonUSDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=stt_AssetBackedSecuritiesStudentLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=stt_AssetbackedSecuritiesCollateralizedLoanObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=stt_NonAgencyCMBSAndRMBSMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_OtherDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: