Segment Information - Information about Company's Segments (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Net interest income	$ 6,852	$ 7,115	$ 5,822
Noninterest income	2,427	2,528	2,357
Provision for credit losses	610	645	517
Salaries and employee benefits	3,162	2,997	2,787
Depreciation and amortization	53	62	56
Depreciation and amortization of premises and equipment	316	304	282
Income (loss) before taxes	3,310	3,619	2,612
Income tax expense (benefit)	722	878	620
Net income (loss)	2,588	2,741	1,992
Taxable-equivalent adjustment	50	54	39
Operating Segments
Segment Reporting Information [Line Items]
Net interest income	6,852	7,115	5,822
Noninterest income	2,427	2,528	2,357
Total revenue	9,279	9,643	8,179
Provision for credit losses	610
Salaries and employee benefits	3,162		2,787
Depreciation and amortization of premises and equipment	508	497	435
Other direct expenses	1,689	1,885	1,828
Indirect expense (income)	0	0	0
Income (loss) before taxes	3,310	3,619	2,612
Income tax expense (benefit)	722	878	620
Net income (loss)	2,588	2,741	1,992
Average total assets	211,220	205,397	190,252
Commercial Bank
Segment Reporting Information [Line Items]
Other direct expenses	285	275
Average total assets		80,243
Commercial Bank | Operating Segments
Segment Reporting Information [Line Items]
Net interest income	2,212	2,409	2,302
Noninterest income	672	658	588
Total revenue	2,884	3,067	2,890
Provision for credit losses	266	297	66
Salaries and employee benefits	610	577	483
Depreciation and amortization of premises and equipment	39	39	39
Other direct expenses			213
Indirect expense (income)	490	455	389
Income (loss) before taxes	1,194	1,424	1,700
Income tax expense (benefit)	323	385	458
Net income (loss)	871	1,039	1,242
Average total assets	80,864		69,960
Retail Bank
Segment Reporting Information [Line Items]
Other direct expenses	421	465
Income tax expense (benefit)			364
Average total assets		51,213
Retail Bank | Operating Segments
Segment Reporting Information [Line Items]
Net interest income	4,288	4,352	3,008
Noninterest income	810	762	703
Total revenue	5,098	5,114	3,711
Provision for credit losses	288	173	101
Salaries and employee benefits	778	779	694
Depreciation and amortization of premises and equipment	252	249	198
Other direct expenses			386
Indirect expense (income)	1,048	964	929
Income (loss) before taxes	2,311	2,484	1,403
Income tax expense (benefit)	595	646
Net income (loss)	1,716	1,838	1,039
Average total assets	53,043		49,059
Institutional Services and Wealth Management
Segment Reporting Information [Line Items]
Other direct expenses	102	156
Institutional Services and Wealth Management | Operating Segments
Segment Reporting Information [Line Items]
Net interest income	748	700	403
Noninterest income	809	1,005	1,007
Total revenue	1,557	1,705	1,410
Provision for credit losses	6	0	(1)
Salaries and employee benefits	413	405	376
Depreciation and amortization of premises and equipment	9	8	8
Other direct expenses			211
Indirect expense (income)	307	298	272
Income (loss) before taxes	720	838	544
Income tax expense (benefit)	185	218	142
Net income (loss)	535	620	402
Average total assets	3,800	3,675	3,598
All Other | Operating Segments
Segment Reporting Information [Line Items]
Net interest income	(396)	(346)	109
Noninterest income	136	103	59
Total revenue	(260)	(243)	168
Provision for credit losses	50	175	351
Salaries and employee benefits	1,361	1,236	1,234
Depreciation and amortization of premises and equipment	208	201	190
Other direct expenses	881	989	1,018
Indirect expense (income)	(1,845)	(1,717)	(1,590)
Income (loss) before taxes	(915)	(1,127)	(1,035)
Income tax expense (benefit)	(381)	(371)	(344)
Net income (loss)	(534)	(756)	(691)
Average total assets	$ 73,513	$ 70,266	$ 67,635