LHFI Considered Impaired (Detail) - USD ($)		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014		Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		$ 287,000,000	$ 319,000,000
Impaired Financing Receivable, Unpaid Principal Balance		3,165,000,000	3,108,000,000
Impaired Financing Receivable, Recorded Investment	[1]	2,876,000,000	2,781,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		2,916,000,000	2,847,000,000		$ 3,175,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	132,000,000	139,000,000		138,000,000
Commercial and Industrial Sector [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		55,000,000	70,000,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	42,000,000	51,000,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		28,000,000	7,000,000
Impaired Financing Receivable, Unpaid Principal Balance		173,000,000	27,000,000
Impaired Financing Receivable, Recorded Investment	[1]	167,000,000	26,000,000
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		58,000,000	84,000,000		75,000,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	[2]	2,000,000	1,000,000		1,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		147,000,000	16,000,000		45,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	5,000,000	1,000,000		1,000,000
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		11,000,000	12,000,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	9,000,000	11,000,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		0	4,000,000
Impaired Financing Receivable, Unpaid Principal Balance		0	4,000,000
Impaired Financing Receivable, Recorded Investment		0	4,000,000	[1]
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		10,000,000	11,000,000		60,000,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method		0	1,000,000	[2]	2,000,000	[2]
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		0	5,000,000		3,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method		0	0		0
Commercial Construction [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		0	0		5,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method		0	0		0
Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		66,000,000	82,000,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	51,000,000	62,000,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		28,000,000	11,000,000
Impaired Financing Receivable, Unpaid Principal Balance		173,000,000	31,000,000
Impaired Financing Receivable, Recorded Investment	[1]	167,000,000	30,000,000
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		68,000,000	95,000,000		135,000,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	[2]	2,000,000	2,000,000		3,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		147,000,000	21,000,000		53,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	5,000,000	1,000,000		1,000,000
Residential Nonguaranteed [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		500,000,000	592,000,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	380,000,000	425,000,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		178,000,000	215,000,000
Impaired Financing Receivable, Unpaid Principal Balance		1,381,000,000	1,381,000,000
Impaired Financing Receivable, Recorded Investment	[1]	1,344,000,000	1,354,000,000
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		390,000,000	437,000,000		449,000,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	[2]	17,000,000	17,000,000		18,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		1,349,000,000	1,357,000,000		1,576,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	65,000,000	78,000,000		76,000,000
Home Equity Line of Credit [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		60,000,000	66,000,000
Impaired Financing Receivable, Unpaid Principal Balance		740,000,000	703,000,000
Impaired Financing Receivable, Recorded Investment	[1]	670,000,000	630,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		682,000,000	644,000,000		649,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	28,000,000	27,000,000		23,000,000
Residential Construction [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		29,000,000	31,000,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	8,000,000	9,000,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		14,000,000	19,000,000
Impaired Financing Receivable, Unpaid Principal Balance		127,000,000	145,000,000
Impaired Financing Receivable, Recorded Investment	[1]	125,000,000	145,000,000
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		11,000,000	12,000,000		21,000,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method		0	0		1,000,000	[2]
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		125,000,000	144,000,000		172,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	8,000,000	8,000,000		10,000,000
Residential Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		529,000,000	623,000,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	388,000,000	434,000,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		252,000,000	300,000,000
Impaired Financing Receivable, Unpaid Principal Balance		2,248,000,000	2,229,000,000
Impaired Financing Receivable, Recorded Investment	[1]	2,139,000,000	2,129,000,000
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		401,000,000	449,000,000		470,000,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	[2]	17,000,000	17,000,000		19,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		2,156,000,000	2,145,000,000		2,397,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	101,000,000	113,000,000		109,000,000
Consumer Other Direct [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		1,000,000	1,000,000
Impaired Financing Receivable, Unpaid Principal Balance		11,000,000	13,000,000
Impaired Financing Receivable, Recorded Investment	[1]	11,000,000	13,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		12,000,000	14,000,000		15,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method		0	0		1,000,000	[2]
Consumer Indirect [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		5,000,000	5,000,000
Impaired Financing Receivable, Unpaid Principal Balance		114,000,000	105,000,000
Impaired Financing Receivable, Recorded Investment	[1]	114,000,000	105,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		125,000,000	113,000,000		89,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	6,000,000	5,000,000		4,000,000
Credit Card Receivable [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		1,000,000	2,000,000
Impaired Financing Receivable, Unpaid Principal Balance		24,000,000	25,000,000
Impaired Financing Receivable, Recorded Investment	[1]	6,000,000	8,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		7,000,000	10,000,000		16,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	1,000,000	1,000,000		1,000,000
Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		7,000,000	8,000,000
Impaired Financing Receivable, Unpaid Principal Balance		149,000,000	143,000,000
Impaired Financing Receivable, Recorded Investment	[1]	131,000,000	126,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		144,000,000	137,000,000		120,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	$ 7,000,000	$ 6,000,000		$ 6,000,000

[1] Amortized cost reflects charge-offs that have been recognized plus other amounts that have been applied to adjust the net book balance.

[2] Of the interest income recognized during December 31, 2015, 2014, and 2013, cash basis interest income was $7 million, $4 million, and $10 million, respectively.