Composition of the Company's Loan Portfolio (Detail) - USD ($) $ in Millions		Jun. 30, 2019		Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other Real Estate	[1]	$ 55		$ 54
Loans held for investment		156,589		151,839
Loans Held for Sale	[2]	2,229		1,468
Finance Leases Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		4,100		4,059
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[3]	72,971		71,137
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		8,655		7,265
Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		2,365		2,538
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Other Real Estate		1		2
Loans held for investment		83,991		80,940
Federal National Mortgage Association (FNMA) Insured Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		439		459
Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[5],[6]	28,794	[4]	28,836	[7]
Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[5]	8,902		9,468
Residential Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[5]	156		184
Federal Family Education Loan Program (FFELP) Guaranteed Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		7,200		7,229
Consumer Other Direct [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		11,817		10,615
Consumer Indirect [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		13,598		12,419
Credit Card Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		1,690		1,689
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		$ 72,598		$ 70,899

[1] Does not include foreclosed real estate related to loans insured by the FHA or guaranteed by the VA. Proceeds due from the FHA and the VA are recorded as a receivable in Other assets in the Consolidated Balance Sheets until the property is conveyed and the funds are received. The receivable related to proceeds due from the FHA and the VA totaled $51 million and $50 million at June 30, 2019 and December 31, 2018, respectively.

[2] Includes $1.7 billion and $1.2 billion of LHFS measured at fair value at June 30, 2019 and December 31, 2018, respectively.

[3] Includes $4.1 billion of sales-type, direct financing, and leveraged leases at both June 30, 2019 and December 31, 2018. Includes $862 million and $796 million of installment loans at June 30, 2019 and December 31, 2018, respectively.

[4] Includes $127 million of LHFI measured at fair value, the majority of which were accruing current.

[5] Excludes $7.2 billion of guaranteed student loans at both June 30, 2019 and December 31, 2018, and $439 million and $459 million of guaranteed residential mortgages at June 30, 2019 and December 31, 2018, respectively, for which there was nominal risk of principal loss due to the government guarantee.

[6] Includes $127 million and $163 million of LHFI measured at fair value at June 30, 2019 and December 31, 2018, respectively.

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