Business Segment Reporting (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) segments		Dec. 31, 2017 USD ($)	[1],[2]	Dec. 31, 2016 USD ($)	[3],[4]
Number of Operating Segments | segments	2
Average Total Loans Held for Investment	$ 145,714		$ 144,216		$ 141,118
Average Total Deposits	159,768		159,549		154,189
Average Total Assets	207,277		204,931		199,004
Average Total Liabilities	183,067		180,630		174,936
Average Total Equity	24,210		24,301		24,068
Interest Income (Expense), Net	5,987		5,633		5,221
Fully Taxable Equivalent Adjustment	88		145		138
Net Interest Income Including Fully Taxable Equivalent Adjustment	6,075	[5]	5,778	[6]	5,359	[7]
Provision for Loan, Lease, and Other Losses	208	[8]	409	[9]	444	[10]
Net Interest Income After Provision For Credit Losses and Taxable Equivalent Adjustment	5,867		5,369		4,915
Noninterest Income	3,226		3,354		3,383
Noninterest Expense	5,673		5,764		5,468
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	3,420		2,959		2,830
Income Tax Expense (Benefit) Including Fully Taxable Equivalent Adjustment Reversal	636	[11]	677	[12]	943	[13]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	2,784		2,282		1,887
Net Income (Loss) Attributable to Noncontrolling Interest	9		9		9
Net Income (Loss) Attributable to Parent	2,775		2,273		1,878
Consumer [Member]
Average Total Loans Held for Investment	75,427		73,578		70,455
Average Total Deposits	111,235		109,298		105,365
Average Total Assets	85,509		83,278		79,971
Average Total Liabilities	112,173		110,271		106,374
Average Total Equity	0		0		0
Interest Income (Expense), Net	4,235		3,906		3,636
Fully Taxable Equivalent Adjustment	0		0		0
Net Interest Income Including Fully Taxable Equivalent Adjustment	4,235	[5]	3,906	[6]	3,636	[7]
Provision for Loan, Lease, and Other Losses	148	[8]	366	[9]	159	[10]
Net Interest Income After Provision For Credit Losses and Taxable Equivalent Adjustment	4,087		3,540		3,477
Noninterest Income	1,804		1,905		2,067
Noninterest Expense	4,017		3,982		3,938
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	1,874		1,463		1,606
Income Tax Expense (Benefit) Including Fully Taxable Equivalent Adjustment Reversal	424	[11]	529	[12]	592	[13]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	1,450		934		1,014
Net Income (Loss) Attributable to Noncontrolling Interest	0		0		0
Net Income (Loss) Attributable to Parent	1,450		934		1,014
Wholesale [Member]
Average Total Loans Held for Investment	70,200		69,394		69,287
Average Total Deposits	48,675		50,155		48,782
Average Total Assets	84,413		83,091		83,168
Average Total Liabilities	55,098		55,762		54,457
Average Total Equity	0		0		0
Interest Income (Expense), Net	2,184		2,029		1,812
Fully Taxable Equivalent Adjustment	86		142		136
Net Interest Income Including Fully Taxable Equivalent Adjustment	2,270	[5]	2,171	[6]	1,948	[7]
Provision for Loan, Lease, and Other Losses	60	[8]	39	[9]	282	[10]
Net Interest Income After Provision For Credit Losses and Taxable Equivalent Adjustment	2,210		2,132		1,666
Noninterest Income	1,534		1,573		1,325
Noninterest Expense	1,720		1,727		1,507
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	2,024		1,978		1,484
Income Tax Expense (Benefit) Including Fully Taxable Equivalent Adjustment Reversal	479	[11]	736	[12]	555	[13]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	1,545		1,242		929
Net Income (Loss) Attributable to Noncontrolling Interest	0		0		0
Net Income (Loss) Attributable to Parent	1,545		1,242		929
Corporate Other [Member]
Average Total Loans Held for Investment	89		1,247		1,379
Average Total Deposits	216		160		115
Average Total Assets	35,630		35,931		33,425
Average Total Liabilities	16,100		14,626		14,179
Average Total Equity	0		0		0
Interest Income (Expense), Net	(190)		14		160
Fully Taxable Equivalent Adjustment	2		3		2
Net Interest Income Including Fully Taxable Equivalent Adjustment	(188)	[5]	17	[6]	162	[7]
Provision for Loan, Lease, and Other Losses	0	[8]	4	[9]	3	[10]
Net Interest Income After Provision For Credit Losses and Taxable Equivalent Adjustment	(188)		13		159
Noninterest Income	57		73		137
Noninterest Expense	(42)		74		38
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(89)		12		258
Income Tax Expense (Benefit) Including Fully Taxable Equivalent Adjustment Reversal	(61)	[11]	(292)	[12]	70	[13]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(28)		304		188
Net Income (Loss) Attributable to Noncontrolling Interest	9		9		9
Net Income (Loss) Attributable to Parent	(37)		295		179
Reconciling Items
Average Total Loans Held for Investment	(2)		(3)		(3)
Average Total Deposits	(358)		(64)		(73)
Average Total Assets	1,725		2,631		2,440
Average Total Liabilities	(304)		(29)		(74)
Average Total Equity	24,210		24,301		24,068
Interest Income (Expense), Net	(242)		(316)		(387)
Fully Taxable Equivalent Adjustment	0		0		0
Net Interest Income Including Fully Taxable Equivalent Adjustment	(242)	[5]	(316)	[6]	(387)	[7]
Provision for Loan, Lease, and Other Losses	0	[8]	0	[9]	0	[10]
Net Interest Income After Provision For Credit Losses and Taxable Equivalent Adjustment	(242)		(316)		(387)
Noninterest Income	(169)		(197)		(146)
Noninterest Expense	(22)		(19)		(15)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(389)		(494)		(518)
Income Tax Expense (Benefit) Including Fully Taxable Equivalent Adjustment Reversal	(206)	[11]	(296)	[12]	(274)	[13]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(183)		(198)		(244)
Net Income (Loss) Attributable to Noncontrolling Interest	0		0		0
Net Income (Loss) Attributable to Parent	$ (183)		$ (198)		$ (244)

[1] During the second quarter of 2018, certain of the Company's business banking clients were transferred from the Wholesale business segment to the Consumer business segment. For all periods prior to the second quarter of 2018, the corresponding financial results have been transferred to the Consumer business segment for comparability purposes.

[2] During the fourth quarter of 2017, the Company sold PAC, the results of which were previously reported within the Wholesale business segment. For all periods prior to January 1, 2018, PAC's financial results, including the gain on sale, have been transferred to Corporate Other for enhanced comparability of the Wholesale business segment excluding PAC.

[3] During the second quarter of 2018, certain of the Company's business banking clients were transferred from the Wholesale business segment to the Consumer business segment. For all periods prior to the second quarter of 2018, the corresponding financial results have been transferred to the Consumer business segment for comparability purposes.

[4] During the fourth quarter of 2017, the Company sold PAC, the results of which were previously reported within the Wholesale business segment. For all periods prior to January 1, 2018, PAC's financial results, including the gain on sale, have been transferred to Corporate Other for enhanced comparability of the Wholesale business segment excluding PAC.

[5] Presented on a matched maturity funds transfer price basis for the segments.

[6] Presented on a matched maturity funds transfer price basis for the segments.

[7] Presented on a matched maturity funds transfer price basis for the segments.

[8] Provision for credit losses represents net charge-offs by segment combined with an allocation to the segments for the provision attributable to quarterly changes in the ALLL and unfunded commitment reserve balances.

[9] Provision for credit losses represents net charge-offs by segment combined with an allocation to the segments for the provision attributable to quarterly changes in the ALLL and unfunded commitment reserve balances.

[10] Provision for credit losses represents net charge-offs by segment combined with an allocation to the segments for the provision attributable to quarterly changes in the ALLL and unfunded commitment reserve balances.

[11] Includes regular provision for income taxes as well as FTE income and tax credit adjustment reversals.

[12] Includes regular provision for income taxes as well as FTE income and tax credit adjustment reversals.

[13] Includes regular provision for income taxes as well as FTE income and tax credit adjustment reversals.