LHFI Considered Impaired (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance		$ 3,053		$ 3,053		$ 3,046
Impaired Financing Receivable, Recorded Investment	[1]	2,822		2,822		2,821
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		197		197		204
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		2,847	$ 2,987	2,866	$ 2,997
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	32	35	62	66
Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		35		35		38
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	33		33		35
Impaired Financing Receivable, Unpaid Principal Balance		195		195		127
Impaired Financing Receivable, Recorded Investment	[1]	182		182		117
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		26		26		19
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		46	127	47	118
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	[2]	1	4	1	4
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		184	153	185	156
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	1	1	2	1
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		47		47		0
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	41		41		0
Impaired Financing Receivable, Unpaid Principal Balance		0		0		21
Impaired Financing Receivable, Recorded Investment	[1]	0		0		21
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		0		0		2
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		42	0	44	0
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method		0	0	0	0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		0	16	0	17
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	0	0	0	0
Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		82		82		38
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	74		74		35
Impaired Financing Receivable, Unpaid Principal Balance		195		195		148
Impaired Financing Receivable, Recorded Investment	[1]	182		182		138
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		26		26		21
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		88	127	91	118
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	[2]	1	4	1	4
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		184	169	185	173
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	1	1	2	1
Residential Nonguaranteed [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		481		481		458
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	385		385		363
Impaired Financing Receivable, Unpaid Principal Balance		1,079		1,079		1,133
Impaired Financing Receivable, Recorded Investment	[1]	1,048		1,048		1,103
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		105		105		113
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		383	358	378	356
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	[2]	4	4	7	7
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		1,053	1,180	1,064	1,186
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	13	15	26	31
Home Equity Line of Credit [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance		900		900		953
Impaired Financing Receivable, Recorded Investment	[1]	847		847		895
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		51		51		54
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		849	859	854	864
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	9	8	18	16
Residential Construction [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		12		12		15
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	7		7		9
Impaired Financing Receivable, Unpaid Principal Balance		87		87		93
Impaired Financing Receivable, Recorded Investment	[1]	83		83		90
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		6		6		7
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		7	9	7	9
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	[2]	0	0	0	0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		84	101	85	101
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	1	1	3	2
Consumer Other Direct [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance		58		58		59
Impaired Financing Receivable, Recorded Investment	[1]	58		58		59
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		1		1		1
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		58	58	58	59
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	1	1	2	2
Consumer Indirect [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance		131		131		123
Impaired Financing Receivable, Recorded Investment	[1]	130		130		122
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		7		7		7
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		133	120	137	125
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	2	1	3	3
Credit Card Receivable [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance		28		28		26
Impaired Financing Receivable, Recorded Investment	[1]	8		8		7
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		1		1		1
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		8	6	7	6
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	0	0	0	0
Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		493		493		473
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	392		392		372
Impaired Financing Receivable, Unpaid Principal Balance		2,283		2,283		2,387
Impaired Financing Receivable, Recorded Investment	[1]	2,174		2,174		2,276
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		171		171		$ 183
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		390	367	385	365
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	[2]	4	4	7	7
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		2,185	2,324	2,205	2,341
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	$ 26	$ 26	$ 52	$ 54

[1] Carrying value 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 each of the three and six months ended June 30, 2018 and 2017, cash basis interest income was immaterial.