Business Segment Reporting (Detail) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($) segments		Mar. 31, 2018 USD ($)	[1]
Number of Operating Segments | segments	2
Average Total Loans Held for Investment	$ 154,258		$ 142,920
Average Total Deposits	159,921		159,169
Average Total Assets	217,403		204,132
Average Total Liabilities	192,937		179,527
Average Total Equity	24,466		24,605
Interest Income (Expense), Net	1,544		1,441
Fully Taxable Equivalent Adjustment	23		20
Net Interest Income Including Fully Taxable Equivalent Adjustment	1,567	[2]	1,461	[3]
Provision for Loan, Lease, and Other Losses	153	[4]	28	[5]
Net Interest Income After Provision For Credit Losses and Taxable Equivalent Adjustment	1,414		1,433
Noninterest Income	784		796
Noninterest Expense	1,489		1,417
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	709		812
Income Tax Expense (Benefit) Including Fully Taxable Equivalent Adjustment Reversal	127	[6]	167	[7]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	582		645
Net Income (Loss) Attributable to Noncontrolling Interest	2		2
Net Income (Loss) Attributable to Parent	580		643
Consumer [Member]
Average Total Loans Held for Investment	78,683		74,840
Average Total Deposits	112,245		109,469
Average Total Assets	88,033		84,272
Average Total Liabilities	113,180		110,341
Average Total Equity	0		0
Interest Income (Expense), Net	1,076		998
Fully Taxable Equivalent Adjustment	0		0
Net Interest Income Including Fully Taxable Equivalent Adjustment	1,076	[2]	998	[3]
Provision for Loan, Lease, and Other Losses	83	[4]	58	[5]
Net Interest Income After Provision For Credit Losses and Taxable Equivalent Adjustment	993		940
Noninterest Income	446		450
Noninterest Expense	1,017		1,001
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	422		389
Income Tax Expense (Benefit) Including Fully Taxable Equivalent Adjustment Reversal	96	[6]	87	[7]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	326		302
Net Income (Loss) Attributable to Noncontrolling Interest	0		0
Net Income (Loss) Attributable to Parent	326		302
Wholesale [Member]
Average Total Loans Held for Investment	75,488		68,000
Average Total Deposits	47,850		49,687
Average Total Assets	90,122		81,726
Average Total Liabilities	54,384		55,499
Average Total Equity	0		0
Interest Income (Expense), Net	546		514
Fully Taxable Equivalent Adjustment	22		20
Net Interest Income Including Fully Taxable Equivalent Adjustment	568	[2]	534	[3]
Provision for Loan, Lease, and Other Losses	70	[4]	(30)	[5]
Net Interest Income After Provision For Credit Losses and Taxable Equivalent Adjustment	498		564
Noninterest Income	364		340
Noninterest Expense	462		450
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	400		454
Income Tax Expense (Benefit) Including Fully Taxable Equivalent Adjustment Reversal	95	[6]	107	[7]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	305		347
Net Income (Loss) Attributable to Noncontrolling Interest	0		0
Net Income (Loss) Attributable to Parent	305		347
Corporate Other [Member]
Average Total Loans Held for Investment	88		84
Average Total Deposits	259		197
Average Total Assets	37,822		35,680
Average Total Liabilities	25,720		13,864
Average Total Equity	0		0
Interest Income (Expense), Net	(78)		(30)
Fully Taxable Equivalent Adjustment	1		1
Net Interest Income Including Fully Taxable Equivalent Adjustment	(77)	[2]	(29)	[3]
Provision for Loan, Lease, and Other Losses	0	[4]	0	[5]
Net Interest Income After Provision For Credit Losses and Taxable Equivalent Adjustment	(77)		(29)
Noninterest Income	19		38
Noninterest Expense	14		(29)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(72)		38
Income Tax Expense (Benefit) Including Fully Taxable Equivalent Adjustment Reversal	(24)	[6]	16	[7]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(48)		22
Net Income (Loss) Attributable to Noncontrolling Interest	2		2
Net Income (Loss) Attributable to Parent	(50)		20
Reconciling Items
Average Total Loans Held for Investment	(1)		(4)
Average Total Deposits	(433)		(184)
Average Total Assets	1,426		2,454
Average Total Liabilities	(347)		(177)
Average Total Equity	24,466		24,605
Interest Income (Expense), Net	0		(41)
Fully Taxable Equivalent Adjustment	0		(1)
Net Interest Income Including Fully Taxable Equivalent Adjustment	0	[2]	(42)	[3]
Provision for Loan, Lease, and Other Losses	0	[4]	0	[5]
Net Interest Income After Provision For Credit Losses and Taxable Equivalent Adjustment	0		(42)
Noninterest Income	(45)		(32)
Noninterest Expense	(4)		(5)
Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest	(41)		(69)
Income Tax Expense (Benefit) Including Fully Taxable Equivalent Adjustment Reversal	(40)	[6]	(43)	[7]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	(1)		(26)
Net Income (Loss) Attributable to Noncontrolling Interest	0		0
Net Income (Loss) Attributable to Parent	$ (1)		$ (26)

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

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

[4] 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.

[5] 3 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] Includes regular provision for income taxes as well as FTE income and tax credit adjustment reversals.

[7] 4 Includes regular provision for income taxes as well as FTE income and tax credit adjustment reversals.