Composition of the Company's Loan Portfolio (Detail) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[1]	$ 136,442	$ 133,112
Loans Held for Sale	[2]	1,838	3,232
Commercial and Industrial Sector [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		67,062	65,440
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		6,236	6,741
Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		1,954	1,211
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		75,252	73,392
Federal National Mortgage Association (FNMA) Insured Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		629	632
Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[3],[4]	24,744	23,443
Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[3]	13,171	14,264
Residential Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[3]	384	436
Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		38,928	38,775
Federal Family Education Loan Program (FFELP) Guaranteed Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		4,922	4,827
Consumer Other Direct [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[5]	6,127	4,573
Consumer Indirect [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[5]	10,127	10,644
Credit Card Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[5]	1,086	901
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		$ 22,262	$ 20,945

[1] Includes loans of consolidated VIEs of $246 million and $288 million at December 31, 2015 and December 31, 2014, respectively.

[2] Includes $1.5 billion and $1.9 billion of LHFS measured at fair value at December 31, 2015 and 2014, respectively.

[3] Excludes $629 million and $632 million of guaranteed residential loans at December 31, 2015 and 2014, respectively.

[4] Includes $257 million of loans measured at fair value, the majority of which were accruing current.

[5] Excludes $4.9 billion and $4.8 billion of guaranteed student loans at December 31, 2015 and 2014, respectively.