Segment Information (Summary of Segment Information) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Net interest income:
Net interest income	$ 457,995	$ 299,294
Net interest income, change in contribution	$ 158,701
Net interest income, percent change in contribution	53.00%
Provision for credit losses:
Provision for credit losses	$ 23,045	4,106
Provision for credit losses, change in contribution	18,939
Non-interest income:
Non-interest income	107,769	162,790
Non-interest income, change in contribution	$ (55,021)
Non-interest income, percent change in contribution	(34.00%)
Net revenue:
Net revenue	$ 565,764	462,084
Net revenue, change in contribution	$ 103,680
Net revenue, percent change in contribution	22.00%
Segment profit:
Segment profit	$ 180,198	127,391
Segment profit, change in contribution	$ 52,807
Segment profit, percent change in contribution	41.00%
Segment assets:
Segment assets	$ 52,873,511	50,250,661	$ 52,949,649
Segment assets, change in contribution	$ 2,622,850
Segment assets, percent change in contribution	5.00%
Community banking
Segment profit:
Segment profit	$ 134,232	90,099
Segment profit, change in contribution	$ 44,133
Segment profit, percent change in contribution	49.00%
Segment assets:
Segment assets	$ 41,611,980	40,050,015
Segment assets, change in contribution	$ 1,561,965
Segment assets, percent change in contribution	4.00%
Specialty finance
Segment profit:
Segment profit	$ 36,737	29,604
Segment profit, change in contribution	$ 7,133
Segment profit, percent change in contribution	24.00%
Segment assets:
Segment assets	$ 9,841,044	8,624,501
Segment assets, change in contribution	$ 1,216,543
Segment assets, percent change in contribution	14.00%
Wealth management
Segment profit:
Segment profit	$ 9,229	7,688
Segment profit, change in contribution	$ 1,541
Segment profit, percent change in contribution	20.00%
Segment assets:
Segment assets	$ 1,420,487	1,576,145
Segment assets, change in contribution	$ (155,658)
Segment assets, percent change in contribution	(10.00%)
Operating Segments
Net interest income:
Net interest income	$ 449,154	292,361
Net interest income, change in contribution	$ 156,793
Net interest income, percent change in contribution	54.00%
Provision for credit losses:
Provision for credit losses	$ 23,045	4,106
Provision for credit losses, change in contribution	18,939
Non-interest income:
Non-interest income	124,820	176,588
Non-interest income, change in contribution	$ (51,768)
Non-interest income, percent change in contribution	(29.00%)
Net revenue:
Net revenue	$ 573,974	468,949
Net revenue, change in contribution	$ 105,025
Net revenue, percent change in contribution	22.00%
Operating Segments | Community banking
Net interest income:
Net interest income	$ 369,848	228,615
Net interest income, change in contribution	$ 141,233
Net interest income, percent change in contribution	62.00%
Provision for credit losses:
Provision for credit losses	$ 21,099	4,118
Provision for credit losses, change in contribution	16,981
Non-interest income:
Non-interest income	68,733	121,888
Non-interest income, change in contribution	$ (53,155)
Non-interest income, percent change in contribution	(44.00%)
Net revenue:
Net revenue	$ 438,581	350,503
Net revenue, change in contribution	$ 88,078
Net revenue, percent change in contribution	25.00%
Operating Segments | Specialty finance
Net interest income:
Net interest income	$ 70,351	55,370
Net interest income, change in contribution	$ 14,981
Net interest income, percent change in contribution	27.00%
Provision for credit losses:
Provision for credit losses	$ 1,946	(12)
Provision for credit losses, change in contribution	1,958
Non-interest income:
Non-interest income	25,790	24,122
Non-interest income, change in contribution	$ 1,668
Non-interest income, percent change in contribution	7.00%
Net revenue:
Net revenue	$ 96,141	79,492
Net revenue, change in contribution	$ 16,649
Net revenue, percent change in contribution	21.00%
Operating Segments | Wealth management
Net interest income:
Net interest income	$ 8,955	8,376
Net interest income, change in contribution	$ 579
Net interest income, percent change in contribution	7.00%
Provision for credit losses:
Provision for credit losses	$ 0	0
Provision for credit losses, change in contribution	$ 0
Provision for credit losses, percent change in contribution	0.00%
Non-interest income:
Non-interest income	$ 30,297	30,578
Non-interest income, change in contribution	$ (281)
Non-interest income, percent change in contribution	(1.00%)
Net revenue:
Net revenue	$ 39,252	38,954
Net revenue, change in contribution	$ 298
Net revenue, percent change in contribution	1.00%
Intersegment Eliminations
Net interest income:
Net interest income	$ 8,841	6,933
Net interest income, change in contribution	$ 1,908
Net interest income, percent change in contribution	28.00%
Provision for credit losses:
Provision for credit losses	$ 0	0
Provision for credit losses, change in contribution	$ 0
Provision for credit losses, percent change in contribution	0.00%
Non-interest income:
Non-interest income	$ (17,051)	(13,798)
Non-interest income, change in contribution	$ (3,253)
Non-interest income, percent change in contribution	24.00%
Net revenue:
Net revenue	$ (8,210)	$ (6,865)
Net revenue, change in contribution	$ (1,345)
Net revenue, percent change in contribution	20.00%