Commitments, Guarantees, and Contingencies (Narrative) (Details)	12 Months Ended					1 Months Ended	0 Months Ended			12 Months Ended						108 Months Ended					1 Months Ended
	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Aug. 31, 2009 customer	Dec. 31, 2013 State Street Global Advisors USD ($) claim	Jan. 31, 2014 State Street Global Advisors Subsequent Event USD ($)	Aug. 31, 2009 Securities Finance USD ($)	Dec. 31, 2013 Securities Finance USD ($)	Jun. 30, 2013 Securities Finance USD ($)	Dec. 31, 2013 Foreign Exchange USD ($)	Dec. 31, 2012 Foreign Exchange USD ($)	Dec. 31, 2011 Foreign Exchange USD ($)	Dec. 31, 2010 Foreign Exchange USD ($)	Dec. 31, 2009 Foreign Exchange USD ($)	Dec. 31, 2008 Foreign Exchange USD ($)	Dec. 31, 2009 Foreign Exchange USD ($)	Dec. 31, 2013 Putative Class Action claim	Dec. 31, 2013 Shareholder Litigation USD ($) shareholder complaint	Dec. 31, 2013 Transition Management USD ($)	Dec. 31, 2013 Transition Management Legal Reserve USD ($)	Jan. 31, 2014 Transition Management Subsequent Event claim	Jan. 31, 2014 Transition Management Subsequent Event Regulatory Matter USD ($)	Jan. 31, 2014 Transition Management Subsequent Event Regulatory Matter GBP (£)	Dec. 31, 2013 Investment Servicing USD ($)	Dec. 31, 2013 Accrued expenses and other liabilities USD ($)	Dec. 31, 2012 Accrued expenses and other liabilities USD ($)
Loss Contingencies [Line Items]
Unfunded commitments to extend credit	$ 21,300,000,000	$ 17,860,000,000
Unfunded commitments to extend credit, short term	75.00%
Percent of fair market value that must be maintained in collateral	100.00%
Cash collateral provided for securities lending	11,290,000,000	6,830,000,000
Cash collateral received in connection to securities finance activities																									6,620,000,000	4,990,000,000
Legal reserves																				119,000,000
Claims settled																					6
Number of pending claims					2												2
Settlement, amount						10,000,000																37,800,000	22,900,000
Litigation reserve					15,000,000			10,000,000										12,500,000	13,000,000					4,600,000
Number of suits from related participants of agency securities lending program				2
Loss contingency, damages sought, value							120,000,000
Realized loss on sales of securities									11,000,000
Actual damages asserted by attorney general																100,000,000
Estimated indirect foreign exchange revenue										285,000,000	248,000,000	331,000,000	336,000,000	369,000,000	462,000,000
Shareholder related class action complaints pending in Boston Federal Court																		3
Number of class action complaints pending in Boston Federal Court brought on behalf of State Street shareholders																		1
Number of class action complaints pending in Boston Federal Court brought on behalf of State Street participants and beneficiaries of State Street Salary Savings Program																		2
Unrecognized tax benefits	$ 158,000,000	$ 95,000,000	$ 125,000,000