Loans and Related Allowance for Credit Losses (Home Equity and Residential Real Estate Credit Quality Indicators) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total loans, net	[1]	$ 321,381		$ 321,381		$ 321,508
Gross charge-offs
Total		376	$ 233	1,081	$ 808
Residential real estate
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one		2,195		2,195		5,335
Year two		4,838		4,838		10,064
Year three		9,649		9,649		15,484
Year four		14,854		14,854		6,832
Year five		6,472		6,472		2,270
Prior		8,964		8,964		7,559
Total loans, net		46,972		46,972		47,544
Gross charge-offs
Year two						2
Year three						1
Year four						1
Prior				2		4
Total				2		8
Home equity
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year two
Year three						162
Year four		151		151		1,918
Year five		1,764		1,764		868
Prior		3,003		3,003		2,592
Revolving Loans		8,297		8,297		8,265
Revolving Loans Converted to Term		12,755		12,755		12,345
Total loans, net		25,970		25,970		26,150
Gross charge-offs
Prior				1		4
Revolving Loans				13		7
Revolving Loans Converted to Term				13		10
Total				27		21
Greater than or equal to 780 | Residential real estate
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one		1,302		1,302		3,206
Year two		3,337		3,337		7,797
Year three		7,639		7,639		12,197
Year four		11,832		11,832		5,035
Year five		4,726		4,726		1,492
Prior		5,042		5,042		4,004
Total loans, net		33,878		33,878		33,731
Greater than or equal to 780 | Home equity
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year two
Year three						102
Year four		96		96		1,254
Year five		1,177		1,177		489
Prior		1,845		1,845		1,605
Revolving Loans		4,626		4,626		4,604
Revolving Loans Converted to Term		6,203		6,203		6,083
Total loans, net		13,947		13,947		14,137
720 to 779 | Residential real estate
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one		775		775		1,482
Year two		960		960		1,659
Year three		1,484		1,484		2,389
Year four		2,152		2,152		1,107
Year five		1,081		1,081		432
Prior		1,609		1,609		1,388
Total loans, net		8,061		8,061		8,457
720 to 779 | Home equity
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year two
Year three						38
Year four		37		37		423
Year five		368		368		216
Prior		606		606		488
Revolving Loans		2,225		2,225		2,222
Revolving Loans Converted to Term		3,265		3,265		3,225
Total loans, net		6,501		6,501		6,612
660 to 719 | Residential real estate
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one		114		114		400
Year two		273		273		508
Year three		411		411		657
Year four		618		618		334
Year five		342		342		171
Prior		816		816		721
Total loans, net		2,574		2,574		2,791
660 to 719 | Home equity
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year two
Year three						17
Year four		15		15		174
Year five		157		157		110
Prior		302		302		271
Revolving Loans		1,198		1,198		1,207
Revolving Loans Converted to Term		2,039		2,039		1,894
Total loans, net		3,711		3,711		3,673
Less than 660 | Residential real estate
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one		3		3		93
Year two		116		116		71
Year three		85		85		133
Year four		148		148		122
Year five		102		102		82
Prior		703		703		680
Total loans, net		1,157		1,157		1,181
Less than 660 | Home equity
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year two
Year three						5
Year four		3		3		65
Year five		60		60		52
Prior		243		243		220
Revolving Loans		241		241		223
Revolving Loans Converted to Term		1,202		1,202		1,089
Total loans, net		1,749		1,749		1,654
No FICO score available | Residential real estate
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one		1		1		140
Year two		135		135		9
Year three		8		8		92
Year four		88		88		168
Year five		154		154		56
Prior		292		292		266
Total loans, net		678		678		731
No FICO score available | Home equity
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year three
Year four						2
Year five		2		2		1
Prior		7		7		8
Revolving Loans		7		7		9
Revolving Loans Converted to Term		46		46		54
Total loans, net		62		62		74
Government insured or guaranteed loans | Residential real estate
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one						14
Year two		17		17		20
Year three		22		22		16
Year four		16		16		66
Year five		67		67		37
Prior		502		502		500
Total loans, net		624		624		653
Greater than 100% | Residential real estate
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one		5		5		15
Year two		68		68		139
Year three		113		113		79
Year four		59		59		31
Year five		23		23		10
Prior		31		31		28
Total loans, net		299		299		302
Greater than 100% | Home equity
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year two
Year three						1
Year four		1		1		12
Year five		12		12		6
Prior		15		15		14
Revolving Loans		333		333		306
Revolving Loans Converted to Term		328		328		309
Total loans, net		689		689		648
Greater than or equal to 80% to 100% | Residential real estate
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one		608		608		1,665
Year two		633		633		1,928
Year three		963		963		955
Year four		581		581		221
Year five		176		176		69
Prior		134		134		92
Total loans, net		3,095		3,095		4,930
Greater than or equal to 80% to 100% | Home equity
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year two
Year three						4
Year four		5		5		40
Year five		32		32		17
Prior		30		30		22
Revolving Loans		1,042		1,042		1,116
Revolving Loans Converted to Term		1,552		1,552		1,743
Total loans, net		2,661		2,661		2,942
Less than 80% | Residential real estate
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one		1,582		1,582		3,585
Year two		4,084		4,084		7,977
Year three		8,551		8,551		14,421
Year four		14,187		14,187		6,514
Year five		6,206		6,206		2,154
Prior		8,294		8,294		6,935
Total loans, net		42,904		42,904		41,586
Less than 80% | Home equity
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year two
Year three						157
Year four		145		145		1,866
Year five		1,720		1,720		845
Prior		2,958		2,958		2,556
Revolving Loans		6,922		6,922		6,843
Revolving Loans Converted to Term		10,875		10,875		10,293
Total loans, net		22,620		22,620		22,560
No LTV available | Residential real estate
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Year one						56
Year two		36		36
Year three						13
Year four		11		11
Year five
Prior		3		3		4
Total loans, net		$ 50		$ 50		$ 73

[1] Our consolidated assets included the following for which we have elected the fair value option: Loans held for sale of $0.7 billion, Loans held for investment of $1.2 billion and Other assets of $0.1 billion at September 30, 2024. Comparable amounts at December 31, 2023 were $0.7 billion, $1.2 billion and $0.1 billion, respectively.