Long-Term Debt (Narrative) (Details) (USD $)	12 Months Ended								12 Months Ended
	Dec. 31, 2013	May 31, 2013	Dec. 31, 2012	Dec. 31, 2013 2.875% notes due 2016	Dec. 31, 2013 4.375% notes due 2021	Nov. 30, 2013 3.70% senior notes due in 2023	May 31, 2013 Senior notes 1.35% due May, 15 2018	May 31, 2013 Subordinated note 3.10% due May, 15 2023	Dec. 31, 2013 4.956% Percent Junior Subordinated Debenture Due 2018	Dec. 31, 2013 4.30% notes due 2014	Dec. 31, 2013 5.375% notes due 2017	Dec. 31, 2013 Floating-rate notes due 2014	Dec. 31, 2013 7.35% notes due 2026	Dec. 31, 2013 Extendible notes due 2014	Dec. 31, 2013 5.25% subordinated notes due 2018	Dec. 31, 2013 5.30% subordinated notes due 2016	Dec. 31, 2013 State Street Capital Trusts I And IV trust	Dec. 31, 2013 One Lincoln Street Headquarters Building and Parking Garage	Dec. 31, 2012 One Lincoln Street Headquarters Building and Parking Garage	Dec. 31, 2013 Office Building in the UK	Dec. 31, 2012 Office Building in the UK	Dec. 31, 2013 Construction in Progress on New Building and Premises and Equipment	Dec. 31, 2012 Construction in Progress on New Building and Premises and Equipment
Debt Instrument [Line Items]
Face amount		$ 1,500,000,000.0				$ 1,000,000,000.0	$ 500,000,000	$ 1,000,000,000.0
Senior notes interest rate percentage				2.875%	4.375%	3.70%	1.35%	3.10%
Bank Notes Authorized	5,000,000,000
Senior Debt Securities Authorized Under Board Authority	4,100,000,000
Subordinated Debt Authorized	1,500,000,000.0
Number of statutory business trusts																	2
Issued trust preferred capital securities																	955,000,000
Number of years interest payments received on debentures deferral																	5 years
Capital lease included in long term debt	$ 646,000,000		$ 576,000,000															$ 363,000,000	$ 387,000,000	$ 267,000,000	$ 269,000,000	$ 158,000,000	$ 50,000,000
Subordinated borrowing interest rate									4.956%	4.30%	5.375%		7.35%		5.25%	5.30%
Subordinated borrowing, due date									Mar. 15, 2018	May 30, 2014	Apr. 30, 2017	Mar. 07, 2014	Jun. 15, 2026	Jan. 13, 2014
Maximum Maturity Date for Extension Option														Jan. 15, 2016
Date at Which Optional Redemptions of Debt are Allowable														Jan. 15, 2015
Percent of Principal Amount Redeemed Under Redemption Option														100.00%