Reportable Operating Segments - Selected Business Segment Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Selected business segment financial information
Net interest income (expense)	$ 156,707	$ 157,148	$ 463,985	$ 484,334
(Provision) benefit for credit losses	(7,400)	(7,500)	(15,500)	(21,300)
Net interest income after provision for credit losses	149,307	149,648	448,485	463,034
Noninterest income	53,288	46,097	156,427	142,468
Noninterest expense	(126,147)	(119,383)	(377,046)	(358,831)
Income before provision for income taxes	76,448	76,362	227,866	246,671
(Provision) benefit for income taxes	(14,956)	(18,141)	(50,233)	(59,190)
Net income	61,492	58,221	177,633	187,481
Retail Banking
Selected business segment financial information
Net interest income (expense)	126,335	119,070	379,088	332,227
(Provision) benefit for credit losses	(3,390)	(2,359)	(8,294)	(6,913)
Net interest income after provision for credit losses	122,945	116,711	370,794	325,314
Noninterest income	26,585	24,834	78,916	72,898
Noninterest expense	(73,016)	(77,873)	(222,281)	(231,313)
Income before provision for income taxes	76,514	63,672	227,429	166,899
(Provision) benefit for income taxes	(18,519)	(15,209)	(55,070)	(39,836)
Net income	57,995	48,463	172,359	127,063
Commercial Banking
Selected business segment financial information
Net interest income (expense)	47,222	45,913	137,622	128,348
(Provision) benefit for credit losses	(3,726)	(3,565)	(9,114)	(10,447)
Net interest income after provision for credit losses	43,496	42,348	128,508	117,901
Noninterest income	21,666	18,858	58,247	55,832
Noninterest expense	(21,691)	(24,976)	(69,999)	(79,832)
Income before provision for income taxes	43,471	36,230	116,756	93,901
(Provision) benefit for income taxes	(9,325)	(8,334)	(25,017)	(21,546)
Net income	34,146	27,896	91,739	72,355
Treasury and Other
Selected business segment financial information
Net interest income (expense)	(16,850)	(7,835)	(52,725)	23,759
(Provision) benefit for credit losses	(284)	(1,576)	1,908	(3,940)
Net interest income after provision for credit losses	(17,134)	(9,411)	(50,817)	19,819
Noninterest income	5,037	2,405	19,264	13,738
Noninterest expense	(31,440)	(16,534)	(84,766)	(47,686)
Income before provision for income taxes	(43,537)	(23,540)	(116,319)	(14,129)
(Provision) benefit for income taxes	12,888	5,402	29,854	2,192
Net income	$ (30,649)	$ (18,138)	$ (86,465)	$ (11,937)