LHFI Considered Impaired (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance		$ 2,309		$ 2,309		$ 2,890
Impaired Financing Receivable, Recorded Investment	[1]	2,180		2,180		2,611
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		179		179		167
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		2,193	$ 2,780	2,219	$ 2,809
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	26	30	85	94
Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		48		48		132
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	39		39		79
Impaired Financing Receivable, Unpaid Principal Balance		311		311		81
Impaired Financing Receivable, Recorded Investment	[1]	300		300		70
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		71		71		13
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		40	44	41	45
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	[2]	0	0	0	1
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		303	177	305	176
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	2	0	8	3
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		0		0		10
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	0		0		0
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		0	20	0	20
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		0	21	0	22
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		48		48		142
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	39		39		79
Impaired Financing Receivable, Unpaid Principal Balance		311		311		81
Impaired Financing Receivable, Recorded Investment	[1]	300		300		70
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		71		71		13
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		40	64	41	65
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	[2]	0	0	0	1
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		303	198	305	198
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	2	0	8	3
Residential Nonguaranteed [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		354		354		501
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	283		283		397
Impaired Financing Receivable, Unpaid Principal Balance		561		561		1,006
Impaired Financing Receivable, Recorded Investment	[1]	561		561		984
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		54		54		96
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		284	381	287	386
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	[2]	4	4	12	11
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		562	1,027	565	1,031
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	8	13	28	39
Home Equity Line of Credit [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance		753		753		849
Impaired Financing Receivable, Recorded Investment	[1]	721		721		799
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		41		41		44
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		723	824	732	833
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	8	9	25	27
Residential Construction [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		7		7		12
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	4		4		7
Impaired Financing Receivable, Unpaid Principal Balance		70		70		79
Impaired Financing Receivable, Recorded Investment	[1]	68		68		76
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		5		5		6
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		4	7	4	7
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		68	80	69	82
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	1	1	3	4
Consumer Other Direct [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance		57		57		57
Impaired Financing Receivable, Recorded Investment	[1]	57		57		57
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		1		1		1
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		58	57	58	58
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	1	1	3	3
Consumer Indirect [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance		136		136		133
Impaired Financing Receivable, Recorded Investment	[1]	135		135		133
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		4		4		5
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		139	134	147	141
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	2	2	5	5
Credit Card Receivable [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance		12		12		30
Impaired Financing Receivable, Recorded Investment	[1]	12		12		9
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		3		3		2
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		12	8	11	8
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	0	0	1	1
Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		361		361		513
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	287		287		404
Impaired Financing Receivable, Unpaid Principal Balance		1,589		1,589		2,154
Impaired Financing Receivable, Recorded Investment	[1]	1,554		1,554		2,058
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		108		108		$ 154
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		288	388	291	393
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method	[2]	4	4	12	11
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		1,562	2,130	1,582	2,153
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method	[2]	$ 20	$ 26	$ 65	$ 79

[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 the three and nine months ended September 30, 2019, cash basis interest income was immaterial and $9 million, respectively. Of the interest income recognized during the three and nine months ended September 30, 2018, cash basis interest income was immaterial.