Long-Term Debt - Narrative (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) trust	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Bank notes authorized	$ 5,000,000,000
Senior debt authorized by BOD	4,000,000,000
Subordinated debt available for issuance	500,000,000
Capital lease obligation	194,000,000	$ 231,000,000
Building and Parking Garage
Debt Instrument [Line Items]
Capital lease obligation	$ 278,000,000	308,000,000
State Street Capital Trusts I And I V
Debt Instrument [Line Items]
Number of statutory business trusts | trust	2
Junior subordinated debenture owed to unconsolidated subsidiary trust		$ 955,000,000
Maximum deferral period available on interest payments	5 years