Commitments, Contingencies, Guarantees, and Others - Litigation (Details) $ in Millions	1 Months Ended						3 Months Ended		20 Months Ended
	Sep. 30, 2015 claim	Mar. 31, 2015 claim	Apr. 30, 2014 patent	Dec. 31, 2013 claim patent	Jul. 31, 2012 USD ($)	Feb. 28, 2009 USD ($) Contract MortgageLoan	Mar. 31, 2017 USD ($) claim	Jul. 31, 2012 USD ($) summon trust	Jul. 31, 2015 claim
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss							$ 200
Intellectual Ventures Corp
Loss Contingencies [Line Items]
Number of claims dismissed | claim	4	1		2			3		3
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
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