Payment Status for the LHFI Portfolio (Detail) - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2019		Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Document Period End Date		Sep. 30, 2019
Accruing Current		$ 155,545		$ 148,548
Accruing 30-89 Days Past Due		917		1,113
Accruing 90+ Days Past Due		1,393		1,652
Financing Receivable, Nonaccrual	[1]	600	[2]	526	[3]
Total	[4]	158,455		151,839
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Current		72,955		70,901
Accruing 30-89 Days Past Due		55		64
Accruing 90+ Days Past Due		14		15
Financing Receivable, Nonaccrual		350	[2]	157	[3]
Total	[5]	73,374		71,137
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Current		9,486		7,259
Accruing 30-89 Days Past Due		3		3
Accruing 90+ Days Past Due		1		1
Financing Receivable, Nonaccrual		1	[2]	2	[3]
Total		9,491		7,265
Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Current		2,142		2,538
Accruing 30-89 Days Past Due		0		0
Accruing 90+ Days Past Due		0		0
Financing Receivable, Nonaccrual		0	[2]	0	[3]
Total		2,142		2,538
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Current		84,583		80,698
Accruing 30-89 Days Past Due		58		67
Accruing 90+ Days Past Due		15		16
Financing Receivable, Nonaccrual		351	[2]	159	[3]
Total		85,007		80,940
Federal National Mortgage Association (FNMA) Insured Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Current		131		125
Accruing 30-89 Days Past Due		25		39
Accruing 90+ Days Past Due		301		295
Financing Receivable, Nonaccrual		0	[2],[6]	0	[3],[7]
Total		457		459
Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Current		28,620	[8]	28,552	[9]
Accruing 30-89 Days Past Due		55	[8]	70	[9]
Accruing 90+ Days Past Due		10	[8]	10	[9]
Financing Receivable, Nonaccrual		125	[2],[8]	204	[3],[9]
Total	[10],[11]	28,810	[8]	28,836	[9]
Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Current		8,534		9,268
Accruing 30-89 Days Past Due		61		62
Accruing 90+ Days Past Due		1		0
Financing Receivable, Nonaccrual		100	[2]	138	[3]
Total	[11]	8,696		9,468
Residential Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Current		135		170
Accruing 30-89 Days Past Due		1		3
Accruing 90+ Days Past Due		0		0
Financing Receivable, Nonaccrual		8	[2]	11	[3]
Total	[11]	144		184
Federal Family Education Loan Program (FFELP) Guaranteed Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Current		5,563		5,236
Accruing 30-89 Days Past Due		543		685
Accruing 90+ Days Past Due		1,040		1,308
Financing Receivable, Nonaccrual		0	[2],[6]	0	[3],[7]
Total		7,146		7,229
Consumer Other Direct [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Current		12,362		10,559
Accruing 30-89 Days Past Due		53		45
Accruing 90+ Days Past Due		5		4
Financing Receivable, Nonaccrual		11	[2]	7	[3]
Total		12,431		10,615
Consumer Indirect [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Current		13,951		12,286
Accruing 30-89 Days Past Due		103		125
Accruing 90+ Days Past Due		1		1
Financing Receivable, Nonaccrual		5	[2]	7	[3]
Total		14,060		12,419
Credit Card Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Current		1,666		1,654
Accruing 30-89 Days Past Due		18		17
Accruing 90+ Days Past Due		20		18
Financing Receivable, Nonaccrual		0	[2]	0	[3]
Total		1,704		1,689
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accruing Current		70,962		67,850
Accruing 30-89 Days Past Due		859		1,046
Accruing 90+ Days Past Due		1,378		1,636
Financing Receivable, Nonaccrual		249	[2]	367	[3]
Total		$ 73,448		$ 70,899

[1] Nonaccruing restructured LHFI are included in total nonaccrual LHFI/NPLs.

[2] Includes nonaccruing LHFI past due 90 days or more of $306 million. Nonaccruing LHFI past due fewer than 90 days include nonaccrual LHFI modified in TDRs, performing second lien LHFI where the first lien loan is nonperforming, and certain energy-related commercial LHFI.

[3] Includes nonaccruing LHFI past due 90 days or more of $306 million. Nonaccruing LHFI past due fewer than 90 days include nonaccrual LHFI modified in TDRs, performing second lien LHFI where the first lien loan is nonperforming, and certain energy-related commercial LHFI.

[4] Includes LHFI of consolidated VIEs of $136 million and $153 million at September 30, 2019 and December 31, 2018, respectively.

[5] Includes $4.0 billion and $4.1 billion of sales-type, direct financing, and leveraged leases at September 30, 2019 and December 31, 2018, respectively. Includes $817 million and $796 million of installment loans at September 30, 2019 and December 31, 2018, respectively.

[6] Guaranteed LHFI are not placed on nonaccrual status regardless of delinquency because collection of principal and interest is reasonably assured by the government. 

[7] Guaranteed LHFI are not placed on nonaccrual status regardless of delinquency because collection of principal and interest is reasonably assured by the government.

[8] Includes $124 million of LHFI measured at fair value, the majority of which were accruing current.

[9] Includes $163 million of LHFI measured at fair value, the majority of which were accruing current.

[10] Includes $124 million and $163 million measured at fair value at September 30, 2019 and December 31, 2018, respectively.

[11] Excludes $7.1 billion and $7.2 billion of guaranteed student loans and $457 million and $459 million of guaranteed residential mortgages at September 30, 2019 and December 31, 2018, respectively, for which there was nominal risk of principal loss due to the government guarantee.