Reportable Operating Segments - Selected Business Segment Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Selected business segment financial information
Net interest income	$ 159,939	$ 145,147	$ 327,186	$ 279,019
(Provision) Benefit for credit losses	(5,000)	(1,000)	(13,800)	4,747
Net interest income after provision for credit losses	154,939	144,147	313,386	283,766
Noninterest income	47,348	44,137	96,371	85,517
Noninterest expense	(120,881)	(109,175)	(239,448)	(213,217)
Income before provision for income taxes	81,406	79,109	170,309	156,066
(Provision) benefit for income taxes	(18,964)	(19,749)	(41,049)	(38,987)
Net income	62,442	59,360	129,260	117,079
Retail Banking
Selected business segment financial information
Net interest income	104,237	107,368	213,157	201,416
(Provision) Benefit for credit losses	(1,991)	(386)	(4,554)	1,455
Net interest income after provision for credit losses	102,246	106,982	208,603	202,871
Noninterest income	23,797	22,485	48,064	45,800
Noninterest expense	(77,597)	(73,357)	(153,440)	(143,577)
Income before provision for income taxes	48,446	56,110	103,227	105,094
(Provision) benefit for income taxes	(11,361)	(13,896)	(24,627)	(26,046)
Net income	37,085	42,214	78,600	79,048
Commercial Banking
Selected business segment financial information
Net interest income	41,496	36,826	82,435	71,914
(Provision) Benefit for credit losses	(3,009)	(614)	(6,882)	1,928
Net interest income after provision for credit losses	38,487	36,212	75,553	73,842
Noninterest income	19,086	20,415	36,974	39,070
Noninterest expense	(27,086)	(26,962)	(54,856)	(53,467)
Income before provision for income taxes	30,487	29,665	57,671	59,445
(Provision) benefit for income taxes	(6,882)	(7,251)	(13,212)	(14,504)
Net income	23,605	22,414	44,459	44,941
Treasury and Other
Selected business segment financial information
Net interest income	14,206	953	31,594	5,689
(Provision) Benefit for credit losses			(2,364)	1,364
Net interest income after provision for credit losses	14,206	953	29,230	7,053
Noninterest income	4,465	1,237	11,333	647
Noninterest expense	(16,198)	(8,856)	(31,152)	(16,173)
Income before provision for income taxes	2,473	(6,666)	9,411	(8,473)
(Provision) benefit for income taxes	(721)	1,398	(3,210)	1,563
Net income	$ 1,752	$ (5,268)	$ 6,201	$ (6,910)