Composition of the Company's Loan Portfolio (Detail) - USD ($) $ in Millions		Sep. 30, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[1]	$ 133,560	$ 133,112
Loans Held for Sale	[2]	2,032	3,232
Commercial and Industrial Sector [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		65,371	65,440
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		73,302	73,392
Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		38,788	38,775
Federal Family Education Loan Program (FFELP) Guaranteed Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		4,588	4,827
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		21,470	20,945
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		6,168	6,741
Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		1,763	1,211
Federal National Mortgage Association (FNMA) Insured Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		627	632
Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[3],[4]	24,351	23,443
Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[3]	13,416	14,264
Residential Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[3]	394	436
Consumer Other Direct [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[5]	5,771	4,573
Consumer Indirect [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[5]	10,119	10,644
Credit Card Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[5]	$ 992	$ 901

[1] Includes loans of consolidated VIEs of $256 million and $288 million at September 30, 2015 and December 31, 2014, respectively.

[2] Includes $1.9 billion of LHFS measured at fair value at both September 30, 2015 and December 31, 2014.

[3] Excludes $627 million and $632 million of guaranteed residential loans at September 30, 2015 and December 31, 2014, respectively.

[4] Includes $262 million of loans measured at fair value, the majority of which were accruing current.

[5] Excludes $4.6 billion and $4.8 billion of guaranteed student loans at September 30, 2015 and December 31, 2014, respectively.