Financial Derivatives (Gains (Losses) on Derivatives Not Designated As Hedging Instruments under GAAP) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net	$ 440	$ 135	$ 502
Residential Mortgages [Member]
Derivative [Line Items]
Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net	237	63	396
Residential Mortgages [Member] | Residential Mortgage Servicing Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net	240	(223)	269
Residential Mortgages [Member] | Loan Sales Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net	(3)	286	127
Commercial Mortgage Banking [Member]
Derivative [Line Items]
Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net	81	10	32
Commercial Mortgage Banking [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net	82	12	35
Commercial Mortgage Banking [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net	(1)	(2)	(3)
Customer Contracts [Member]
Derivative [Line Items]
Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net	87	225	182
Customer Contracts [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net	41	149	106
Customer Contracts [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net	(1)	(1)	(3)
Customer Contracts [Member] | Equity Contract [Member]
Derivative [Line Items]
Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net		(3)	(4)
Customer Contracts [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net	47	80	83
Other Risk Management Activity [Member]
Derivative [Line Items]
Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net	35	(163)	(108)
Other Risk Management Activity [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net	(19)	3	(11)
Other Risk Management Activity [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net			(1)
Other Risk Management Activity [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net	188	2	(2)
Other Risk Management Activity [Member] | Other Contract [Member]
Derivative [Line Items]
Derivative Instruments Not Designated As Hedging Instruments Gain Loss Net	$ (134)	$ (168)	$ (94)