Financial Derivatives (Derivatives Not Designated As Hedging Instruments under GAAP) (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Derivative Notional Amount	$ 347,976,000,000	$ 340,317,000,000
Derivative Asset, Fair Value	4,941,000,000	5,234,000,000
Derivative Liability, Fair Value	3,802,000,000	4,027,000,000
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Notional Amount	52,074,000,000	49,061,000,000
Derivative Asset, Fair Value	1,159,000,000	1,261,000,000
Derivative Liability, Fair Value	174,000,000	186,000,000
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Notional Amount	295,902,000,000	291,256,000,000
Derivative Asset, Fair Value	3,782,000,000	3,973,000,000
Derivative Liability, Fair Value	3,628,000,000	3,841,000,000
Not Designated as Hedging Instrument [Member] | Residential Mortgages [Member]
Derivative [Line Items]
Derivative Notional Amount	73,891,000,000	76,102,000,000
Derivative Asset, Fair Value	823,000,000	846,000,000
Derivative Liability, Fair Value	447,000,000	437,000,000
Not Designated as Hedging Instrument [Member] | Residential Mortgages [Member] | Residential Mortgage Servicing Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	65,728,000,000	68,976,000,000
Derivative Asset, Fair Value	789,000,000	814,000,000
Derivative Liability, Fair Value	439,000,000	416,000,000
Not Designated as Hedging Instrument [Member] | Residential Mortgages [Member] | Loan Sales Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	8,163,000,000	7,126,000,000
Derivative Asset, Fair Value	34,000,000	32,000,000
Derivative Liability, Fair Value	8,000,000	21,000,000
Not Designated as Hedging Instrument [Member] | Commercial Mortgage Banking [Member]
Derivative [Line Items]
Derivative Notional Amount	24,091,000,000	26,290,000,000
Derivative Asset, Fair Value	88,000,000	85,000,000
Derivative Liability, Fair Value	52,000,000	59,000,000
Not Designated as Hedging Instrument [Member] | Commercial Mortgage Banking [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Derivative Notional Amount	77,000,000	95,000,000
Not Designated as Hedging Instrument [Member] | Commercial Mortgage Banking [Member] | Commercial Mortgage Banking Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	24,014,000,000	26,195,000,000
Derivative Asset, Fair Value	88,000,000	85,000,000
Derivative Liability, Fair Value	52,000,000	59,000,000
Not Designated as Hedging Instrument [Member] | Customer Contracts [Member]
Derivative [Line Items]
Derivative Notional Amount	192,621,000,000	183,474,000,000
Derivative Asset, Fair Value	2,812,000,000	2,956,000,000
Derivative Liability, Fair Value	2,661,000,000	2,834,000,000
Not Designated as Hedging Instrument [Member] | Customer Contracts [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	10,888,000,000	12,547,000,000
Derivative Asset, Fair Value	194,000,000	223,000,000
Derivative Liability, Fair Value	198,000,000	240,000,000
Not Designated as Hedging Instrument [Member] | Customer Contracts [Member] | Risk Participation Agreement [Member]
Derivative [Line Items]
Derivative Notional Amount	5,026,000,000	5,124,000,000
Derivative Asset, Fair Value	2,000,000	2,000,000
Derivative Liability, Fair Value	4,000,000	4,000,000
Not Designated as Hedging Instrument [Member] | Customer Contracts [Member] | Customer Related Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	176,707,000,000	165,803,000,000
Derivative Asset, Fair Value	2,616,000,000	2,731,000,000
Derivative Liability, Fair Value	2,459,000,000	2,590,000,000
Not Designated as Hedging Instrument [Member] | Other Risk Management Activity [Member]
Derivative [Line Items]
Derivative Notional Amount	5,299,000,000	5,390,000,000
Derivative Asset, Fair Value	59,000,000	86,000,000
Derivative Liability, Fair Value	468,000,000	511,000,000
Not Designated as Hedging Instrument [Member] | Other Risk Management Activity [Member] | Interest Rate Contracts [Member]
Derivative [Line Items]
Derivative Notional Amount		833,000,000
Derivative Asset, Fair Value		1,000,000
Not Designated as Hedging Instrument [Member] | Other Risk Management Activity [Member] | Credit Default Swap [Member]
Derivative [Line Items]
Derivative Notional Amount	15,000,000	15,000,000
Not Designated as Hedging Instrument [Member] | Other Risk Management Activity [Member] | Foreign Exchange Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	2,742,000,000	2,661,000,000
Derivative Asset, Fair Value	59,000,000	85,000,000
Derivative Liability, Fair Value	6,000,000	1,000,000
Not Designated as Hedging Instrument [Member] | Other Risk Management Activity [Member] | Other Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	2,542,000,000	1,881,000,000
Derivative Liability, Fair Value	462,000,000	510,000,000
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Residential Mortgage Servicing Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	37,505,000,000	32,459,000,000
Derivative Asset, Fair Value	758,000,000	777,000,000
Derivative Liability, Fair Value	416,000,000	394,000,000
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Commercial Mortgage Banking Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	3,945,000,000	3,801,000,000
Derivative Asset, Fair Value	77,000,000	67,000,000
Derivative Liability, Fair Value	46,000,000	48,000,000
Not Designated as Hedging Instrument [Member] | Interest Rate Swap [Member] | Customer Related Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	157,041,000,000	146,008,000,000
Derivative Asset, Fair Value	2,507,000,000	2,632,000,000
Derivative Liability, Fair Value	2,433,000,000	2,559,000,000
Not Designated as Hedging Instrument [Member] | Interest Rate Swaption [Member] | Residential Mortgage Servicing Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	650,000,000	1,498,000,000
Derivative Asset, Fair Value	27,000,000	29,000,000
Derivative Liability, Fair Value	14,000,000	22,000,000
Not Designated as Hedging Instrument [Member] | Interest Rate Swaption [Member] | Commercial Mortgage Banking Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	439,000,000	439,000,000
Derivative Asset, Fair Value		2,000,000
Derivative Liability, Fair Value		1,000,000
Not Designated as Hedging Instrument [Member] | Interest Rate Swaption [Member] | Customer Related Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	4,363,000,000	3,361,000,000
Derivative Asset, Fair Value	86,000,000	62,000,000
Derivative Liability, Fair Value	13,000,000	12,000,000
Not Designated as Hedging Instrument [Member] | Future [Member] | Residential Mortgage Servicing Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	17,653,000,000	22,084,000,000
Not Designated as Hedging Instrument [Member] | Future [Member] | Loan Sales Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	20,000,000	58,000,000
Not Designated as Hedging Instrument [Member] | Future [Member] | Commercial Mortgage Banking Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	18,454,000,000	19,913,000,000
Not Designated as Hedging Instrument [Member] | Future [Member] | Customer Related Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	1,673,000,000	3,112,000,000
Not Designated as Hedging Instrument [Member] | Future Options [Member] | Residential Mortgage Servicing Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	6,000,000,000	12,225,000,000
Derivative Asset, Fair Value		4,000,000
Derivative Liability, Fair Value	1,000,000
Not Designated as Hedging Instrument [Member] | Residential Mortgage Loan Commitment [Member] | Loan Sales Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	1,580,000,000	1,852,000,000
Derivative Asset, Fair Value	16,000,000	22,000,000
Not Designated as Hedging Instrument [Member] | Commercial Mortgage Loan Commitment [Member] | Commercial Mortgage Banking Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	1,176,000,000	2,042,000,000
Derivative Asset, Fair Value	11,000,000	16,000,000
Derivative Liability, Fair Value	6,000,000	10,000,000
Not Designated as Hedging Instrument [Member] | Bond Option [Member] | Loan Sales Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	200,000,000	300,000,000
Derivative Asset, Fair Value	2,000,000
Not Designated as Hedging Instrument [Member] | Caps Floors Sold [Member] | Customer Related Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	5,337,000,000	4,846,000,000
Derivative Liability, Fair Value	11,000,000	16,000,000
Not Designated as Hedging Instrument [Member] | Caps Floors Purchased [Member] | Customer Related Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	6,383,000,000	6,339,000,000
Derivative Asset, Fair Value	18,000,000	34,000,000
Not Designated as Hedging Instrument [Member] | Mortgage Backed Securities Commitments [Member] | Residential Mortgage Servicing Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	3,920,000,000	710,000,000
Derivative Asset, Fair Value	4,000,000	4,000,000
Derivative Liability, Fair Value	8,000,000
Not Designated as Hedging Instrument [Member] | Mortgage Backed Securities Commitments [Member] | Loan Sales Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	6,363,000,000	4,916,000,000
Derivative Asset, Fair Value	16,000,000	10,000,000
Derivative Liability, Fair Value	8,000,000	21,000,000
Not Designated as Hedging Instrument [Member] | Mortgage Backed Securities Commitments [Member] | Customer Related Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Notional Amount	1,910,000,000	2,137,000,000
Derivative Asset, Fair Value	5,000,000	3,000,000
Derivative Liability, Fair Value	$ 2,000,000	$ 3,000,000