Commitments, Contingencies, Guarantees, and Others - Litigation (Details) (USD $)	1 Months Ended			3 Months Ended	1 Months Ended		3 Months Ended
	Jan. 31, 2014 claim	Dec. 31, 2013 claim	Jul. 31, 2012	Mar. 31, 2008	Apr. 30, 2014 patent	Feb. 28, 2009 Plaintiff MortgageLoan Contract	Jul. 31, 2012 summon trust	Dec. 31, 2014	Sep. 30, 2010	Jul. 31, 2013
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss								$ 250,000,000
Interchange Litigation
Loss Contingencies [Line Items]
Indemnification guarantees fair value								0
Intellectual Ventures Corp
Loss Contingencies [Line Items]
Number of claims dismissed	1	2
Pending Litigation | Interchange Litigation
Loss Contingencies [Line Items]
Litigation settlement, attributable to reporting entity and third party			6,600,000,000
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)				(91,000,000)
Pending Litigation | Intellectual Ventures Corp
Loss Contingencies [Line Items]
Number of patents not infringed		1			2
GreenPoint Subsidiary | Pending Litigation | U.S. Bank Litigation
Loss Contingencies [Line Items]
Number of contracts breached						2
Number of mortgage loans sold to third party under litigation						30,000
Mortgage loans sold to third party, face amount under litigation						1,800,000,000
Number of plaintiffs						2
GreenPoint Subsidiary | Pending Litigation | DBSP Litigation
Loss Contingencies [Line Items]
Mortgage loans sold to third party, face amount under litigation									353,000,000
GreenPoint Subsidiary | Pending Litigation | FHFA Litigation
Loss Contingencies [Line Items]
Mortgage loans sold to third party, face amount under litigation			3,400,000,000				3,400,000,000
Number of summons filed							3
Number of residential mortgage backed securities trusts							3
GreenPoint Subsidiary | Pending Litigation | LXS Trust Litigation
Loss Contingencies [Line Items]
Mortgage loans sold to third party, face amount under litigation										$ 915,000,000