Composition of the Company's Loan Portfolio (Detail) - USD ($) $ in Millions		Dec. 31, 2018		Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[1]	$ 151,839		$ 143,181
Loans Held for Sale	[2]	1,468		2,290
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[3]	71,137		66,356
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		7,265		5,317
Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		2,538		3,804
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		80,940		75,477
Federal National Mortgage Association (FNMA) Insured Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		459		560
Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[5],[6]	28,836	[4]	27,136	[7]
Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[5]	9,468		10,626
Residential Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[5]	184		298
Federal Family Education Loan Program (FFELP) Guaranteed Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		7,229		6,600
Consumer Other Direct [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		10,615		8,729
Consumer Indirect [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		12,419		12,140
Credit Card Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		1,689		1,582
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		$ 70,899		$ 67,704

[1] Includes loans of consolidated VIEs of $153 million and $179 million at December?31, 2018 and December?31, 2017, respectively.

[2] Includes $1.2 billion and $1.6 billion of LHFS measured at fair value at December 31, 2018 and 2017, respectively.

[3] Includes $4.1 billion and $3.7 billion of lease financing, and $796 million and $778 million of installment loans at December 31, 2018 and 2017, respectively.

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

[5] Excludes $7.2 billion and $6.6 billion of guaranteed student loans and $459 million and $560 million of guaranteed residential mortgages at December 31, 2018 and 2017, respectively, for which there was nominal risk of principal loss due to the government guarantee.

[6] Includes $163 million and $196 million of LHFI measured at fair value at December 31, 2018 and 2017, respectively.

[7] Includes $196 million of loans measured at fair value, the majority of which were accruing current.