Commitments and Guarantees - Contractual Amounts of Credit-Related Off-Balance Sheet Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Unfunded credit facilities	$ 33,026	$ 34,213
Indemnified securities financing	385,740	440,875
Standby letters of credit	$ 3,237	$ 3,330

Aggregate Fair Value Of Indemnified Securities On Loan

No definition available.

Name:	stt_AggregateFairValueOfIndemnifiedSecuritiesOnLoan
Namespace Prefix:	stt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant