Fair Value Measurements (Assets And Liabilities Recorded At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		$ 12,398	$ 12,045
Derivative assets		317	275
Derivative Liability	[1]	66	223
Derivative liabilities		141	269
U.S. Treasury and other U.S. government agency securities
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		2,792	2,727
Residential mortgage-backed securities
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale	[2]	9,606	9,318
Recurring
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		12,398	12,045
Derivative assets		317	275
Total assets at fair value		12,864	12,451
Derivative liabilities		141	269
Deferred compensation plan liabilities		95	88
Total liabilities at fair value		236	357
Recurring | Level 1
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		2,792	2,727
Derivative assets		0	0
Total assets at fair value		2,941	2,858
Derivative Liability		0	0
Deferred compensation plan liabilities		95	88
Total liabilities at fair value		95	88
Recurring | Level 2
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		9,606	9,318
Derivative assets		295	266
Total assets at fair value		9,901	9,584
Derivative Liability		141	269
Deferred compensation plan liabilities		0	0
Total liabilities at fair value		141	269
Recurring | Level 3
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		0	0
Derivative assets		22	9
Total assets at fair value		22	9
Derivative Liability		0	0
Deferred compensation plan liabilities		0	0
Total liabilities at fair value		0	0
Recurring | Interest rate contracts
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		211	67
Derivative Liability		39	70
Recurring | Interest rate contracts | Level 1
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets			0
Derivative Liability		0	0
Recurring | Interest rate contracts | Level 2
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		189	58
Derivative Liability		39	70
Recurring | Interest rate contracts | Level 3
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		22	9
Derivative Liability		0	0
Recurring | Energy derivative contracts
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		96	189
Derivative Liability		92	186
Recurring | Energy derivative contracts | Level 1
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		0	0
Derivative Liability		0	0
Recurring | Energy derivative contracts | Level 2
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		96	189
Derivative Liability		92	186
Recurring | Energy derivative contracts | Level 3
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		0	0
Derivative Liability		0	0
Recurring | Foreign exchange contracts
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		10	19
Derivative Liability		10	13
Recurring | Foreign exchange contracts | Level 1
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		0	0
Derivative Liability		0	0
Recurring | Foreign exchange contracts | Level 2
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		10	19
Derivative Liability		10	13
Recurring | Foreign exchange contracts | Level 3
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Derivative assets		0	0
Derivative Liability		0	0
Recurring | Deferred compensation plan assets
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities		95	88
Recurring | Deferred compensation plan assets | Level 1
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities		95	88
Recurring | Deferred compensation plan assets | Level 2
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities		0	0
Recurring | Deferred compensation plan assets | Level 3
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities		0	0
Recurring | Equity and other non-debt securities
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities		54
Recurring | Equity and other non-debt securities | Level 1
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities		54
Recurring | Equity and other non-debt securities | Level 2
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities		0
Recurring | Equity and other non-debt securities | Level 3
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities		0
Recurring | U.S. Treasury and other U.S. government agency securities
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		2,792	2,727
Recurring | U.S. Treasury and other U.S. government agency securities | Level 1
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		2,792	2,727
Recurring | U.S. Treasury and other U.S. government agency securities | Level 2
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		0	0
Recurring | U.S. Treasury and other U.S. government agency securities | Level 3
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Investment securities available-for-sale		0	0
Recurring | Residential mortgage-backed securities
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities			43
Investment securities available-for-sale	[2]	9,606	9,318
Recurring | Residential mortgage-backed securities | Level 1
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities			43
Investment securities available-for-sale	[2]	0	0
Recurring | Residential mortgage-backed securities | Level 2
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities			0
Investment securities available-for-sale	[2]	9,606	9,318
Recurring | Residential mortgage-backed securities | Level 3
Assets and Liabilities Measured at Fair Value on a Recurring Basis [Line Items]
Other equity securities			0
Investment securities available-for-sale	[2]	$ 0	$ 0

[1] Net derivative assets are included in accrued income and other assets and net derivative liabilities are included in accrued expenses and other liabilities on the Consolidated Balance Sheets. Included in the fair value of net derivative assets and net derivative liabilities are credit valuation adjustments reflecting counterparty credit risk and credit risk of the Corporation. The fair value of net derivative assets included credit valuation adjustments for counterparty credit risk of $9 million and $2 million at December 31, 2019 and 2018, respectively.

[2] Issued and/or guaranteed by U.S. government agencies or U.S. government-sponsored enterprises.