Fair Value (Fair Value Option - Fair Value and Principal Balances) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Loans Held For Sale | Residential Mortgages
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value - Assets	$ 654	$ 1,302
Aggregate Unpaid Principal Balance - Assets	687	1,282
Difference - Assets	(33)	20
Loans Held For Sale | Commercial Mortgage
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value - Assets	276	575
Aggregate Unpaid Principal Balance - Assets	300	580
Difference - Assets	(24)	(5)
Loans Held For Sale | Accruing loans less than 90 days past due | Residential Mortgages
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value - Assets	609	1,249
Aggregate Unpaid Principal Balance - Assets	633	1,219
Difference - Assets	(24)	30
Loans Held For Sale | Accruing loans less than 90 days past due | Commercial Mortgage
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value - Assets	261	575
Aggregate Unpaid Principal Balance - Assets	256	580
Difference - Assets	5	(5)
Loans Held For Sale | Accruing loans 90 days or more past due | Residential Mortgages
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value - Assets	5	6
Aggregate Unpaid Principal Balance - Assets	5	6
Difference - Assets
Loans Held For Sale | Nonaccrual loans | Residential Mortgages
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value - Assets	40	47
Aggregate Unpaid Principal Balance - Assets	49	57
Difference - Assets	(9)	(10)
Loans Held For Sale | Nonaccrual loans | Commercial Mortgage
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value - Assets	15
Aggregate Unpaid Principal Balance - Assets	44
Difference - Assets	(29)
Loans | Residential Mortgages
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value - Assets	1,310	1,501
Aggregate Unpaid Principal Balance - Assets	1,568	1,804
Difference - Assets	(258)	(303)
Loans | Accruing loans less than 90 days past due | Residential Mortgages
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value - Assets	509	487
Aggregate Unpaid Principal Balance - Assets	521	498
Difference - Assets	(12)	(11)
Loans | Accruing loans 90 days or more past due | Residential Mortgages
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value - Assets	155	262
Aggregate Unpaid Principal Balance - Assets	167	278
Difference - Assets	(12)	(16)
Loans | Nonaccrual loans | Residential Mortgages
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value - Assets	646	752
Aggregate Unpaid Principal Balance - Assets	880	1,028
Difference - Assets	(234)	(276)
Other assets
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value - Assets	80	105
Aggregate Unpaid Principal Balance - Assets	80	107
Difference - Assets		(2)
Other borrowed funds
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value - Liabilities	31	30
Aggregate Unpaid Principal Balance - Liabilities	32	30
Difference - Liabilities	(1)
Other liabilities
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair Value - Liabilities	196
Aggregate Unpaid Principal Balance - Liabilities
Difference - Liabilities	$ 196