Business Segment Reporting (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($) segments		Mar. 31, 2017 USD ($)	[1],[2]
Number of Operating Segments | segments	2
Average Total Loans Held for Investment	$ 142,920		$ 143,670
Average Total Deposits	159,169		158,874
Average Total Assets	204,132		204,252
Average Total Liabilities	179,527		180,581
Average Total Equity	24,605		23,671
Interest Income (Expense), Net	1,441		1,366
Fully Taxable Equivalent Adjustment	20		34
Net Interest Income Including Fully Taxable Equivalent Adjustment	1,461	[3]	1,400	[4]
Provision for Loan, Lease, and Other Losses	28	[5]	119	[6]
Net Interest Income After Provision For Credit Losses and Taxable Equivalent Adjustment	1,433		1,281
Noninterest Income	796	[7]	847	[8]
Noninterest Expense	1,417		1,465
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	812		663
Income Tax Expense (Benefit) Including Fully Taxable Equivalent Adjustment Reversal	167	[9]	193
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	645		470
Net Income (Loss) Attributable to Noncontrolling Interest	2		2
Net Income (Loss) Attributable to Parent	643		468
Consumer [Member]
Average Total Loans Held for Investment	74,093		71,147
Average Total Deposits	103,099		101,941
Average Total Assets	83,716		81,265
Average Total Liabilities	103,925		102,896
Average Total Equity	0		0
Interest Income (Expense), Net	961		894
Fully Taxable Equivalent Adjustment	0		0
Net Interest Income Including Fully Taxable Equivalent Adjustment	961	[3]	894	[4]
Provision for Loan, Lease, and Other Losses	60	[5]	88	[6]
Net Interest Income After Provision For Credit Losses and Taxable Equivalent Adjustment	901		806
Noninterest Income	443		464
Noninterest Expense	966		992
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	378		278
Income Tax Expense (Benefit) Including Fully Taxable Equivalent Adjustment Reversal	83	[9]	100
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	295		178
Net Income (Loss) Attributable to Noncontrolling Interest	0		0
Net Income (Loss) Attributable to Parent	295		178
Wholesale [Member]
Average Total Loans Held for Investment	68,741		71,237
Average Total Deposits	56,050		56,866
Average Total Assets	82,472		84,632
Average Total Liabilities	61,902		62,512
Average Total Equity	0		0
Interest Income (Expense), Net	563		527
Fully Taxable Equivalent Adjustment	20		34
Net Interest Income Including Fully Taxable Equivalent Adjustment	583	[3]	561	[4]
Provision for Loan, Lease, and Other Losses	(32)	[5]	32	[6]
Net Interest Income After Provision For Credit Losses and Taxable Equivalent Adjustment	615		529
Noninterest Income	371		401
Noninterest Expense	477		479
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	509		451
Income Tax Expense (Benefit) Including Fully Taxable Equivalent Adjustment Reversal	119	[9]	168
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	390		283
Net Income (Loss) Attributable to Noncontrolling Interest	0		0
Net Income (Loss) Attributable to Parent	390		283
Corporate Other [Member]
Average Total Loans Held for Investment	90		1,286
Average Total Deposits	204		117
Average Total Assets	35,489		35,241
Average Total Liabilities	13,877		15,196
Average Total Equity	0		0
Interest Income (Expense), Net	(28)		26
Fully Taxable Equivalent Adjustment	1		1
Net Interest Income Including Fully Taxable Equivalent Adjustment	(27)	[3]	27	[4]
Provision for Loan, Lease, and Other Losses	0	[5]	0	[6]
Net Interest Income After Provision For Credit Losses and Taxable Equivalent Adjustment	(27)		27
Noninterest Income	14		24
Noninterest Expense	(21)		(2)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	8		53
Income Tax Expense (Benefit) Including Fully Taxable Equivalent Adjustment Reversal	9	[9]	(6)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(1)		59
Net Income (Loss) Attributable to Noncontrolling Interest	2		2
Net Income (Loss) Attributable to Parent	(3)		57
Reconciling Items
Average Total Loans Held for Investment	(4)		0
Average Total Deposits	(184)		(50)
Average Total Assets	2,455		3,114
Average Total Liabilities	(177)		(23)
Average Total Equity	24,605		23,671
Interest Income (Expense), Net	(55)		(81)
Fully Taxable Equivalent Adjustment	(1)		(1)
Net Interest Income Including Fully Taxable Equivalent Adjustment	(56)	[3]	(82)	[4]
Provision for Loan, Lease, and Other Losses	0	[5]	(1)	[6]
Net Interest Income After Provision For Credit Losses and Taxable Equivalent Adjustment	(56)		(81)
Noninterest Income	(32)		(42)
Noninterest Expense	(5)		(4)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(83)		(119)
Income Tax Expense (Benefit) Including Fully Taxable Equivalent Adjustment Reversal	(44)	[9]	(69)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(39)		(50)
Net Income (Loss) Attributable to Noncontrolling Interest	0		0
Net Income (Loss) Attributable to Parent	$ (39)		$ (50)

[1] Beginning in the second quarter of 2017, the Company realigned its business segment structure from three segments to two segments. Specifically, the Company retained the previous composition of the Wholesale Banking segment and changed the basis of presentation of the Consumer Banking and Private Wealth Management segment and Mortgage Banking segment such that those segments were combined into a single Consumer segment. Accordingly, business segment information presented for the three months ended March 31, 2017 has been revised to conform to the new business segment structure and updated internal funds transfer pricing methodology for consistent presentation.

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

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

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

[6] 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.

[7] Amounts are presented in accordance with ASC Topic 606, Revenue from Contracts with Customers.

[8] Amounts for periods prior to January 1, 2018 are presented in accordance with ASC Topic 605, Revenue Recognition, and have not been restated to conform with ASC Topic 606, Revenue from Contracts with Customers.

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