Segment Information - Information about Company's Segments (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Segment Reporting Information [Line Items]
Net Income (Loss)	$ 362,174	$ 447,249
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	1,445,061	1,486,993
Business Banking [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	41,111	46,271
Business Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	141,346	155,903
Business Banking [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	671	669
Commercial Banking [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	144,608	122,638
Commercial Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	289,372	285,912
Commercial Banking [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	863	809
Commercial Real Estate [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	97,610	71,272
Commercial Real Estate [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	202,087	200,843
Commercial Real Estate [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	179	222
Discretionary Portfolio [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	35,385	90,546
Discretionary Portfolio [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	64,727	134,544
Discretionary Portfolio [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	(27,805)	(10,027)
Residential Mortgage Banking [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	28,964	49,611
Residential Mortgage Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	137,444	153,760
Residential Mortgage Banking [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	37,464	22,183
Retail Banking [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	84,164	85,358
Retail Banking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	355,148	346,917
Retail Banking [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	(3)	272
All Other [Member]
Segment Reporting Information [Line Items]
Net Income (Loss)	(69,668)	(18,447)
All Other [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Total Revenues	254,937	209,114
All Other [Member] | Intersegment Activity Eliminated in Consolidated Totals [Member]
Segment Reporting Information [Line Items]
Total Revenues	$ (11,369)	$ (14,128)