Commitments, Contingencies, Guarantees, and Others - Litigation (Details) $ in Millions	1 Months Ended					3 Months Ended
	Apr. 30, 2014 patent	Jan. 31, 2014 claim	Dec. 31, 2013 patent claim	Jul. 31, 2012 USD ($)	Feb. 28, 2009 USD ($) Contract MortgageLoan	Jul. 31, 2012 USD ($) summon trust	Mar. 31, 2008 USD ($)	Sep. 30, 2015 USD ($)	Jul. 31, 2013 USD ($)
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss								$ 250
Intellectual Ventures Corp
Loss Contingencies [Line Items]
Number of claims dismissed | claim		1	2
Pending Litigation | Interchange Litigation
Loss Contingencies [Line Items]
Litigation settlement, attributable to reporting entity and third party				$ 6,600
Litigation settlement, attributable to reporting entity and third party, percent of transactions				0.10%
Litigation settlement, attributable to reporting entity and third party, period of payment of settlement				8 months
Loss accrual increase (decrease)							$ (91)
Pending Litigation | Intellectual Ventures Corp
Loss Contingencies [Line Items]
Number of patents not infringed | patent	2		1
GreenPoint Subsidiary | Pending Litigation | U.S. Bank Litigation
Loss Contingencies [Line Items]
Number of contracts breached | Contract					2
Number of mortgage loans sold to third party under litigation | MortgageLoan					30,000
Mortgage loans sold to third party, face amount under litigation					$ 1,800
GreenPoint Subsidiary | Pending Litigation | FHFA Litigation
Loss Contingencies [Line Items]
Mortgage loans sold to third party, face amount under litigation				$ 3,400		$ 3,400
Number of summons filed | summon						3
Number of residential mortgage backed securities trusts | trust						3
GreenPoint Subsidiary | Pending Litigation | LXS Trust Litigation
Loss Contingencies [Line Items]
Mortgage loans sold to third party, face amount under litigation									$ 915