Segment Information - Information about Company's Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Net Income (Loss)	$ 689,941	$ 646,596	$ 2,258,599	$ 1,226,292
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	2,334,969	2,241,770	7,342,666	5,669,648
Previously Reported [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		2,241,770		5,669,648
Net Income (Loss)		646,596		1,226,292
Revision of Prior Period, Reclassification, Adjustment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		2,241,770		5,669,648
Net Income (Loss)		646,596		1,226,292
Business Banking [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	117,290	92,618	346,704	199,733
Business Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	291,839	241,629	842,571	586,605
Business Banking [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	980	663	2,904	2,060
Business Banking [Member] | Previously Reported [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		241,629		586,605
Net Income (Loss)		94,094		205,741
Business Banking [Member] | Revision of Prior Period, Reclassification, Adjustment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		241,629		586,605
Net Income (Loss)		92,618		199,733
Business Banking [Member] | Impact Of Changes [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)		(1,476)		(6,008)
Commercial Banking [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	167,714	211,225	553,255	501,495
Commercial Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	453,326	509,376	1,420,971	1,236,750
Commercial Banking [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	8,224	802	27,742	2,605
Commercial Banking [Member] | Previously Reported [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		510,549		1,239,300
Net Income (Loss)		214,063		521,749
Commercial Banking [Member] | Revision of Prior Period, Reclassification, Adjustment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		509,376		1,236,750
Net Income (Loss)		211,225		501,495
Commercial Banking [Member] | Impact Of Changes [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		(1,173)		(2,550)
Net Income (Loss)		(2,838)		(20,254)
Commercial Real Estate [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	72,442	110,034	192,539	339,225
Commercial Real Estate [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	231,303	247,114	674,276	705,883
Commercial Real Estate [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	188	249	745	687
Commercial Real Estate [Member] | Previously Reported [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		234,479		676,176
Net Income (Loss)		94,937		314,284
Commercial Real Estate [Member] | Revision of Prior Period, Reclassification, Adjustment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		247,114		705,883
Net Income (Loss)		110,034		339,225
Commercial Real Estate [Member] | Impact Of Changes [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		12,635		29,707
Net Income (Loss)		15,097		24,941
Discretionary Portfolio [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	(21,586)	(6,261)	(93,678)	72,835
Discretionary Portfolio [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	(20,672)	11,641	(78,005)	150,895
Discretionary Portfolio [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	(14,110)	(23,044)	(44,124)	(74,952)
Discretionary Portfolio [Member] | Previously Reported [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		36,622		190,761
Net Income (Loss)		11,813		103,283
Discretionary Portfolio [Member] | Revision of Prior Period, Reclassification, Adjustment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		11,641		150,895
Net Income (Loss)		(6,261)		72,835
Discretionary Portfolio [Member] | Impact Of Changes [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		(24,981)		(39,866)
Net Income (Loss)		(18,074)		(30,448)
Residential Mortgage Banking [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	(14,422)	(2,110)	(41,676)	32,933
Residential Mortgage Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	100,444	95,091	280,654	346,409
Residential Mortgage Banking [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	19,373	35,647	60,599	110,986
Residential Mortgage Banking [Member] | Previously Reported [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		95,091		346,409
Net Income (Loss)		(3,283)		35,028
Residential Mortgage Banking [Member] | Revision of Prior Period, Reclassification, Adjustment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		95,091		346,409
Net Income (Loss)		(2,110)		32,933
Residential Mortgage Banking [Member] | Impact Of Changes [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)		1,173		(2,095)
Retail Banking [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	342,700	182,794	995,927	366,445
Retail Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	876,002	650,227	2,572,410	1,523,992
Retail Banking [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	(35)	(5)	(113)	(12)
Retail Banking [Member] | Previously Reported [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		650,229		1,523,992
Net Income (Loss)		181,639		379,688
Retail Banking [Member] | Revision of Prior Period, Reclassification, Adjustment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		650,227		1,523,992
Net Income (Loss)		182,794		366,445
Retail Banking [Member] | Impact Of Changes [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		(2)
Net Income (Loss)		1,155		(13,243)
All Other [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	25,803	58,296	305,528	(286,374)
All Other [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	402,727	486,692	1,629,789	1,119,114
All Other [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	$ (14,620)	(14,312)	$ (47,753)	(41,374)
All Other [Member] | Previously Reported [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		473,171		1,106,405
Net Income (Loss)		53,333		(333,481)
All Other [Member] | Revision of Prior Period, Reclassification, Adjustment [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		486,692		1,119,114
Net Income (Loss)		58,296		(286,374)
All Other [Member] | Impact Of Changes [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues		13,521		12,709
Net Income (Loss)		$ 4,963		$ 47,107