Composition of the Company's Loan Portfolio (Detail) - USD ($) $ in Millions		Mar. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[1]	$ 139,746	$ 136,442
Loans Held for Sale	[2]	1,911	1,838
Commercial and Industrial Sector [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		68,963	67,062
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		6,034	6,236
Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		2,498	1,954
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		77,495	75,252
Federal National Mortgage Association (FNMA) Insured Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		623	629
Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[3],[4]	25,148	24,744
Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[3]	12,845	13,171
Residential Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[3]	383	384
Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		38,999	38,928
Federal Family Education Loan Program (FFELP) Guaranteed Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		5,265	4,922
Consumer Other Direct [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[5]	6,372	6,127
Consumer Indirect [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[5]	10,522	10,127
Credit Card Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[5]	1,093	1,086
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		$ 23,252	$ 22,262

[1] Includes loans of consolidated VIEs of $237 million and $246 million at March 31, 2016 and December 31, 2015, respectively.

[2] Includes $1.6 billion and $1.5 billion of LHFS measured at fair value at March 31, 2016 and December 31, 2015, respectively.

[3] Excludes $623 million and $629 million of guaranteed residential loans at March 31, 2016 and December 31, 2015, respectively.

[4] Includes $255 million of loans measured at fair value, the majority of which were accruing current.

[5] Excludes $5.3 billion and $4.9 billion of guaranteed student loans at March 31, 2016 and December 31, 2015, respectively.