Cover Page - shares	6 Months Ended
	Jun. 30, 2020	Jul. 22, 2020
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2020
Document Transition Report	false
Entity File Number	001-07511
Entity Registrant Name	STATE STREET CORP
Entity Incorporation, State or Country Code	MA
Entity Tax Identification Number	04-2456637
Entity Address, Address Line One	One Lincoln Street
Entity Address, City or Town	Boston,
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02111
City Area Code	(617)
Local Phone Number	786-3000
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		352,383,250
Amendment Flag	false
Entity Central Index Key	0000093751
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Common Stock
Entity Information [Line Items]
Title of 12(b) Security	Common stock, $1 par value per share
Trading Symbol	STT
Security Exchange Name	NYSE
Series D Preferred Stock, Depository Share
Entity Information [Line Items]
Title of 12(b) Security	Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series D, without par value per share
Trading Symbol	STT.PRD
Security Exchange Name	NYSE
Series G Preferred Stock, Depository Share
Entity Information [Line Items]
Title of 12(b) Security	Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series G, without par value per share
Trading Symbol	STT.PRG
Security Exchange Name	NYSE