Business Segment Reporting - Schedule of Segment Financial Results (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Net interest income	$ 239,434	$ 241,696
Provision for credit losses	10,000	23,250
Noninterest income	159,244	130,200
Noninterest expense	254,804	237,052
Income (loss) before income taxes	133,874	111,594
Income tax expense (benefit)	23,616	19,157
Net income (loss)	110,258	92,437
Average assets	42,017,000	38,503,000
Commercial Banking [Member]
Segment Reporting Information [Line Items]
Net interest income	157,247	151,027
Provision for credit losses	7,520	21,045
Noninterest income	42,966	22,902
Noninterest expense	92,420	84,002
Income (loss) before income taxes	100,273	68,882
Income tax expense (benefit)	17,223	11,646
Net income (loss)	83,050	57,236
Average assets	21,488,000	19,521,000
Institutional Banking [Member]
Segment Reporting Information [Line Items]
Net interest income	49,860	55,085
Provision for credit losses	479	96
Noninterest income	92,716	84,238
Noninterest expense	100,376	89,372
Income (loss) before income taxes	41,721	49,855
Income tax expense (benefit)	7,656	8,504
Net income (loss)	34,065	41,351
Average assets	13,589,000	12,443,000
Personal Banking [Member]
Segment Reporting Information [Line Items]
Net interest income	32,327	35,584
Provision for credit losses	2,001	2,109
Noninterest income	23,562	23,060
Noninterest expense	62,008	63,678
Income (loss) before income taxes	(8,120)	(7,143)
Income tax expense (benefit)	(1,263)	(993)
Net income (loss)	(6,857)	(6,150)
Average assets	$ 6,940,000	$ 6,539,000