Loans and Related Allowance for Credit Losses, Credit Quality Indicators for Residential Mortgage Loans by Vintage (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
Accounts, Notes, Loans and Financing Receivable Textual [Abstract]
High value properties, threshold	$ 1.5		$ 1.5
Total Consumer [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total loans	379,069.0		379,069.0		$ 389,255.0
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Loan charge-offs, loans	1,016.0	$ 887.0	3,095.0	$ 2,466.0
Total Consumer [Member] | Residential mortgage [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Term loans by origination year, current fiscal year, finance receivable	7,974.0		7,974.0		13,203.0
Term loans by origination year, fiscal year before current fiscal year, finance receivable	12,160.0		12,160.0		46,168.0
Term loans by origination year, two years before current fiscal year, finance receivable	44,230.0		44,230.0		62,638.0
Term loans by origination year, three years before current fiscal year, finance receivable	60,119.0		60,119.0		35,257.0
Term loans by origination year, four years before current fiscal year, finance receivable	33,625.0		33,625.0		19,520.0
Term loans by origination year, more than five years before current fiscal year, finance receivable	81,437.0		81,437.0		68,742.0
Revolving loans, finance receivable	6,401.0		6,401.0		8,109.0
Revolving loans converted to term loans, finance receivable	6,730.0		6,730.0		7,087.0
Total loans	252,676.0		252,676.0		260,724.0
Financing Receivable, Excluding Accrued Interest, Allowance for Credit Loss, Writeoff, by Origination Year [Abstract]
Term loans by origination year, current fiscal year, charge-offs			0.0		0.0
Term loans by origination year, fiscal year before current fiscal year, charge-offs			0.0		1.0
Term loans by origination year, two years before current fiscal year, charge-offs			0.0		0.0
Term loans by origination year, three years before current fiscal year, charge-offs			1.0		0.0
Term loans by origination year, four years before current fiscal year, charge-offs			0.0		2.0
Term loans by origination year, more than five years before current fiscal year, charge-offs			22.0		63.0
Revolving loans, charge-offs			1.0		4.0
Revolving loans converted to term loans, charge-offs			26.0		66.0
Loan charge-offs, loans	14.0	$ 37.0	50.0	$ 97.0	136.0
Total Consumer [Member] | Residential mortgage [Member] | Not government insured/guaranteed [Member] | LTV 0-80% [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Term loans by origination year, current fiscal year, finance receivable	7,830.0		7,830.0		12,434.0
Term loans by origination year, fiscal year before current fiscal year, finance receivable	11,627.0		11,627.0		39,624.0
Term loans by origination year, two years before current fiscal year, finance receivable	41,344.0		41,344.0		61,421.0
Term loans by origination year, three years before current fiscal year, finance receivable	59,390.0		59,390.0		34,833.0
Term loans by origination year, four years before current fiscal year, finance receivable	33,303.0		33,303.0		19,123.0
Term loans by origination year, more than five years before current fiscal year, finance receivable	73,997.0		73,997.0		61,043.0
Revolving loans, finance receivable	6,324.0		6,324.0		7,903.0
Revolving loans converted to term loans, finance receivable	6,622.0		6,622.0		6,923.0
Total loans	240,437.0		240,437.0		243,304.0
Total Consumer [Member] | Residential mortgage [Member] | Not government insured/guaranteed [Member] | LTV 80.01-100% [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Term loans by origination year, current fiscal year, finance receivable	62.0		62.0		687.0
Term loans by origination year, fiscal year before current fiscal year, finance receivable	464.0		464.0		6,286.0
Term loans by origination year, two years before current fiscal year, finance receivable	2,715.0		2,715.0		1,065.0
Term loans by origination year, three years before current fiscal year, finance receivable	608.0		608.0		232.0
Term loans by origination year, four years before current fiscal year, finance receivable	147.0		147.0		203.0
Term loans by origination year, more than five years before current fiscal year, finance receivable	270.0		270.0		207.0
Revolving loans, finance receivable	54.0		54.0		103.0
Revolving loans converted to term loans, finance receivable	69.0		69.0		114.0
Total loans	4,389.0		4,389.0		8,897.0
Total Consumer [Member] | Residential mortgage [Member] | Not government insured/guaranteed [Member] | LTV greater than 100% [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Term loans by origination year, current fiscal year, finance receivable	7.0		7.0		51.0
Term loans by origination year, fiscal year before current fiscal year, finance receivable	34.0		34.0		193.0
Term loans by origination year, two years before current fiscal year, finance receivable	110.0		110.0		57.0
Term loans by origination year, three years before current fiscal year, finance receivable	41.0		41.0		33.0
Term loans by origination year, four years before current fiscal year, finance receivable	24.0		24.0		31.0
Term loans by origination year, more than five years before current fiscal year, finance receivable	39.0		39.0		38.0
Revolving loans, finance receivable	12.0		12.0		21.0
Revolving loans converted to term loans, finance receivable	15.0		15.0		24.0
Total loans	282.0		282.0		448.0
Total Consumer [Member] | Residential mortgage [Member] | Not government insured/guaranteed [Member] | No LTV available [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Term loans by origination year, current fiscal year, finance receivable	74.0		74.0		26.0
Term loans by origination year, fiscal year before current fiscal year, finance receivable	26.0		26.0		50.0
Term loans by origination year, two years before current fiscal year, finance receivable	46.0		46.0		56.0
Term loans by origination year, three years before current fiscal year, finance receivable	42.0		42.0		62.0
Term loans by origination year, four years before current fiscal year, finance receivable	57.0		57.0		51.0
Term loans by origination year, more than five years before current fiscal year, finance receivable	152.0		152.0		154.0
Revolving loans, finance receivable	11.0		11.0		82.0
Revolving loans converted to term loans, finance receivable	24.0		24.0		26.0
Total loans	432.0		432.0		507.0
Total Consumer [Member] | Residential mortgage [Member] | Not government insured/guaranteed [Member] | FICO 740 or more [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Term loans by origination year, current fiscal year, finance receivable	7,433.0		7,433.0		12,243.0
Term loans by origination year, fiscal year before current fiscal year, finance receivable	11,393.0		11,393.0		42,550.0
Term loans by origination year, two years before current fiscal year, finance receivable	40,928.0		40,928.0		58,827.0
Term loans by origination year, three years before current fiscal year, finance receivable	56,552.0		56,552.0		33,232.0
Term loans by origination year, four years before current fiscal year, finance receivable	31,668.0		31,668.0		18,000.0
Term loans by origination year, more than five years before current fiscal year, finance receivable	63,638.0		63,638.0		50,938.0
Revolving loans, finance receivable	5,010.0		5,010.0		6,291.0
Revolving loans converted to term loans, finance receivable	3,946.0		3,946.0		4,092.0
Total loans	220,568.0		220,568.0		226,173.0
Total Consumer [Member] | Residential mortgage [Member] | Not government insured/guaranteed [Member] | FICO 700 to 739 [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Term loans by origination year, current fiscal year, finance receivable	360.0		360.0		679.0
Term loans by origination year, fiscal year before current fiscal year, finance receivable	499.0		499.0		2,324.0
Term loans by origination year, two years before current fiscal year, finance receivable	2,127.0		2,127.0		2,510.0
Term loans by origination year, three years before current fiscal year, finance receivable	2,323.0		2,323.0		1,219.0
Term loans by origination year, four years before current fiscal year, finance receivable	1,187.0		1,187.0		888.0
Term loans by origination year, more than five years before current fiscal year, finance receivable	4,729.0		4,729.0		4,478.0
Revolving loans, finance receivable	698.0		698.0		883.0
Revolving loans converted to term loans, finance receivable	913.0		913.0		979.0
Total loans	12,836.0		12,836.0		13,960.0
Total Consumer [Member] | Residential mortgage [Member] | Not government insured/guaranteed [Member] | FICO 660 to 699 [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Term loans by origination year, current fiscal year, finance receivable	75.0		75.0		185.0
Term loans by origination year, fiscal year before current fiscal year, finance receivable	166.0		166.0		843.0
Term loans by origination year, two years before current fiscal year, finance receivable	737.0		737.0		861.0
Term loans by origination year, three years before current fiscal year, finance receivable	782.0		782.0		422.0
Term loans by origination year, four years before current fiscal year, finance receivable	412.0		412.0		310.0
Term loans by origination year, more than five years before current fiscal year, finance receivable	2,315.0		2,315.0		2,261.0
Revolving loans, finance receivable	321.0		321.0		417.0
Revolving loans converted to term loans, finance receivable	551.0		551.0		601.0
Total loans	5,359.0		5,359.0		5,900.0
Total Consumer [Member] | Residential mortgage [Member] | Not government insured/guaranteed [Member] | FICO 620 to 659 [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Term loans by origination year, current fiscal year, finance receivable	15.0		15.0		45.0
Term loans by origination year, fiscal year before current fiscal year, finance receivable	50.0		50.0		227.0
Term loans by origination year, two years before current fiscal year, finance receivable	199.0		199.0		179.0
Term loans by origination year, three years before current fiscal year, finance receivable	176.0		176.0		110.0
Term loans by origination year, four years before current fiscal year, finance receivable	102.0		102.0		66.0
Term loans by origination year, more than five years before current fiscal year, finance receivable	990.0		990.0		978.0
Revolving loans, finance receivable	122.0		122.0		150.0
Revolving loans converted to term loans, finance receivable	286.0		286.0		322.0
Total loans	1,940.0		1,940.0		2,077.0
Total Consumer [Member] | Residential mortgage [Member] | Not government insured/guaranteed [Member] | FICO less than 620 [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Term loans by origination year, current fiscal year, finance receivable	8.0		8.0		11.0
Term loans by origination year, fiscal year before current fiscal year, finance receivable	12.0		12.0		122.0
Term loans by origination year, two years before current fiscal year, finance receivable	139.0		139.0		100.0
Term loans by origination year, three years before current fiscal year, finance receivable	136.0		136.0		64.0
Term loans by origination year, four years before current fiscal year, finance receivable	57.0		57.0		46.0
Term loans by origination year, more than five years before current fiscal year, finance receivable	1,288.0		1,288.0		1,245.0
Revolving loans, finance receivable	149.0		149.0		174.0
Revolving loans converted to term loans, finance receivable	457.0		457.0		464.0
Total loans	2,246.0		2,246.0		2,226.0
Total Consumer [Member] | Residential mortgage [Member] | Not government insured/guaranteed [Member] | No FICO available [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Term loans by origination year, current fiscal year, finance receivable	82.0		82.0		35.0
Term loans by origination year, fiscal year before current fiscal year, finance receivable	31.0		31.0		87.0
Term loans by origination year, two years before current fiscal year, finance receivable	85.0		85.0		122.0
Term loans by origination year, three years before current fiscal year, finance receivable	112.0		112.0		113.0
Term loans by origination year, four years before current fiscal year, finance receivable	105.0		105.0		98.0
Term loans by origination year, more than five years before current fiscal year, finance receivable	1,498.0		1,498.0		1,542.0
Revolving loans, finance receivable	101.0		101.0		194.0
Revolving loans converted to term loans, finance receivable	577.0		577.0		629.0
Total loans	2,591.0		2,591.0		2,820.0
Total Consumer [Member] | Residential mortgage [Member] | Not government insured/guaranteed [Member] | Current-29 days past due [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Term loans by origination year, current fiscal year, finance receivable	7,971.0		7,971.0		13,192.0
Term loans by origination year, fiscal year before current fiscal year, finance receivable	12,137.0		12,137.0		46,065.0
Term loans by origination year, two years before current fiscal year, finance receivable	44,104.0		44,104.0		62,529.0
Term loans by origination year, three years before current fiscal year, finance receivable	60,003.0		60,003.0		35,124.0
Term loans by origination year, four years before current fiscal year, finance receivable	33,485.0		33,485.0		19,364.0
Term loans by origination year, more than five years before current fiscal year, finance receivable	73,376.0		73,376.0		60,391.0
Revolving loans, finance receivable	6,350.0		6,350.0		8,044.0
Revolving loans converted to term loans, finance receivable	6,417.0		6,417.0		6,735.0
Total loans	243,843.0		243,843.0		251,444.0
Total Consumer [Member] | Residential mortgage [Member] | Not government insured/guaranteed [Member] | 30 to 89 days past due [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Term loans by origination year, current fiscal year, finance receivable	2.0		2.0		6.0
Term loans by origination year, fiscal year before current fiscal year, finance receivable	11.0		11.0		70.0
Term loans by origination year, two years before current fiscal year, finance receivable	84.0		84.0		58.0
Term loans by origination year, three years before current fiscal year, finance receivable	59.0		59.0		28.0
Term loans by origination year, four years before current fiscal year, finance receivable	36.0		36.0		30.0
Term loans by origination year, more than five years before current fiscal year, finance receivable	710.0		710.0		724.0
Revolving loans, finance receivable	32.0		32.0		41.0
Revolving loans converted to term loans, finance receivable	138.0		138.0		151.0
Total loans	1,072.0		1,072.0		1,108.0
Total Consumer [Member] | Residential mortgage [Member] | Not government insured/guaranteed [Member] | 90 days or more past due [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Term loans by origination year, current fiscal year, finance receivable	0.0		0.0		0.0
Term loans by origination year, fiscal year before current fiscal year, finance receivable	3.0		3.0		18.0
Term loans by origination year, two years before current fiscal year, finance receivable	27.0		27.0		12.0
Term loans by origination year, three years before current fiscal year, finance receivable	19.0		19.0		8.0
Term loans by origination year, four years before current fiscal year, finance receivable	10.0		10.0		14.0
Term loans by origination year, more than five years before current fiscal year, finance receivable	372.0		372.0		327.0
Revolving loans, finance receivable	19.0		19.0		24.0
Revolving loans converted to term loans, finance receivable	175.0		175.0		201.0
Total loans	625.0		625.0		604.0
Total Consumer [Member] | Residential mortgage [Member] | Government insured or guaranteed [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Term loans by origination year, current fiscal year, finance receivable	1.0		1.0		5.0
Term loans by origination year, fiscal year before current fiscal year, finance receivable	9.0		9.0		15.0
Term loans by origination year, two years before current fiscal year, finance receivable	15.0		15.0		39.0
Term loans by origination year, three years before current fiscal year, finance receivable	38.0		38.0		97.0
Term loans by origination year, four years before current fiscal year, finance receivable	94.0		94.0		112.0
Term loans by origination year, more than five years before current fiscal year, finance receivable	6,979.0		6,979.0		7,300.0
Revolving loans, finance receivable	0.0		0.0		0.0
Revolving loans converted to term loans, finance receivable	0.0		0.0		0.0
Total loans	7,136.0		7,136.0		7,568.0
Total Consumer [Member] | Residential mortgage [Member] | Government insured or guaranteed [Member] | 90 days or more past due [Member]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, by Origination Year [Abstract]
Total loans	$ 2,700.0		$ 2,700.0		$ 2,600.0