LHFI Considered Impaired (Detail) - USD ($)		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance		$ 2,890,000,000		$ 3,046,000,000
Impaired Financing Receivable, Recorded Investment	[1]	2,611,000,000		2,821,000,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		167,000,000		204,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		2,743,000,000		2,866,000,000		$ 3,045,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method		127,000,000	[2]	125,000,000	[2]	128,000,000
Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		132,000,000		38,000,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	79,000,000		35,000,000
Impaired Financing Receivable, Unpaid Principal Balance		81,000,000		127,000,000
Impaired Financing Receivable, Recorded Investment	[1]	70,000,000		117,000,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		13,000,000		19,000,000
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		121,000,000		34,000,000		169,000,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method		7,000,000	[2]	1,000,000	[2]	3,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		71,000,000		112,000,000		170,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method		1,000,000	[2]	2,000,000	[2]	1,000,000
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		10,000,000		0
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	0		0
Impaired Financing Receivable, Unpaid Principal Balance		0		21,000,000
Impaired Financing Receivable, Recorded Investment	[1]	0		21,000,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		0		2,000,000
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		39,000,000		0		0
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method		0		0		0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		0		22,000,000		25,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method		0	[2]	1,000,000	[2]	1,000,000
Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		142,000,000		38,000,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	79,000,000		35,000,000
Impaired Financing Receivable, Unpaid Principal Balance		81,000,000		148,000,000
Impaired Financing Receivable, Recorded Investment	[1]	70,000,000		138,000,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		13,000,000		21,000,000
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		160,000,000		34,000,000		169,000,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method		7,000,000	[2]	1,000,000	[2]	3,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		71,000,000		134,000,000		195,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method		1,000,000	[2]	3,000,000	[2]	2,000,000
Residential Nonguaranteed [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		501,000,000		458,000,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	397,000,000		363,000,000
Impaired Financing Receivable, Unpaid Principal Balance		1,006,000,000		1,133,000,000
Impaired Financing Receivable, Recorded Investment	[1]	984,000,000		1,103,000,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		96,000,000		113,000,000
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		404,000,000		357,000,000		370,000,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method		19,000,000	[2]	15,000,000	[2]	16,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		993,000,000		1,123,000,000		1,251,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method		48,000,000	[2]	58,000,000	[2]	64,000,000
Home Equity Line of Credit [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance		849,000,000		953,000,000
Impaired Financing Receivable, Recorded Investment	[1]	799,000,000		895,000,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		44,000,000		54,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		816,000,000		914,000,000		812,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method		36,000,000	[2]	32,000,000	[2]	29,000,000
Residential Construction [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		12,000,000		15,000,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	7,000,000		9,000,000
Impaired Financing Receivable, Unpaid Principal Balance		79,000,000		93,000,000
Impaired Financing Receivable, Recorded Investment	[1]	76,000,000		90,000,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		6,000,000		7,000,000
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		8,000,000		8,000,000		8,000,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method		1,000,000	[2]	0	[2]	0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		78,000,000		94,000,000		110,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method		3,000,000	[2]	5,000,000	[2]	6,000,000
Consumer Other Direct [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance		57,000,000		59,000,000
Impaired Financing Receivable, Recorded Investment	[1]	57,000,000		59,000,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		1,000,000		1,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		58,000,000		60,000,000		10,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method		4,000,000	[2]	4,000,000	[2]	1,000,000
Consumer Indirect [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance		133,000,000		123,000,000
Impaired Financing Receivable, Recorded Investment	[1]	133,000,000		122,000,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		5,000,000		7,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		147,000,000		136,000,000		114,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method		7,000,000	[2]	6,000,000	[2]	6,000,000
Credit Card Receivable [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, Unpaid Principal Balance		30,000,000		26,000,000
Impaired Financing Receivable, Recorded Investment	[1]	9,000,000		7,000,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		2,000,000		1,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		8,000,000		6,000,000		6,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method		1,000,000	[2]	1,000,000	[2]	1,000,000
Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance		513,000,000		473,000,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	[1]	404,000,000		372,000,000
Impaired Financing Receivable, Unpaid Principal Balance		2,154,000,000		2,387,000,000
Impaired Financing Receivable, Recorded Investment	[1]	2,058,000,000		2,276,000,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment		154,000,000		183,000,000
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment		412,000,000		365,000,000		378,000,000
Impaired Financing Receivable, with No Related Allowance, Interest Income, Accrual Method		20,000,000	[2]	15,000,000	[2]	16,000,000
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment		2,100,000,000		2,333,000,000		2,303,000,000
Impaired Financing Receivable, with Related Allowance, Interest Income, Accrual Method		$ 99,000,000	[2]	$ 106,000,000	[2]	$ 107,000,000

[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 years ended December 31, 2018, 2017, and 2016, cash basis interest income was immaterial.