Reportable Operating Segments - Selected Business Segment Financial Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Selected business segment financial information
Net interest income (expense)	$ 613,549	$ 530,559	$ 535,734
Benefit (Provision) for credit losses	(1,392)	39,000	(121,718)
Net interest income after provision for credit losses	612,157	569,559	414,016
Noninterest income	179,525	184,916	197,380
Noninterest expense	(440,471)	(405,479)	(367,672)
Income before provision for income taxes	351,211	348,996	243,724
(Provision) benefit for income taxes	(85,526)	(83,261)	(57,970)
Net income	265,685	265,735	185,754
Total assets	24,577,223	24,992,410	22,662,831
Retail Banking
Selected business segment financial information
Net interest income (expense)	436,228	385,656	375,145
Benefit (Provision) for credit losses	967	16,267	(52,719)
Net interest income after provision for credit losses	437,195	401,923	322,426
Noninterest income	94,085	91,672	98,026
Noninterest expense	(293,563)	(247,949)	(232,976)
Income before provision for income taxes	237,717	245,646	187,476
(Provision) benefit for income taxes	(58,077)	(58,710)	(43,825)
Net income	179,640	186,936	143,651
Total assets	7,463,002	7,148,376	6,894,602
Commercial Banking
Selected business segment financial information
Net interest income (expense)	157,128	162,997	151,622
Benefit (Provision) for credit losses	1,154	22,452	(53,921)
Net interest income after provision for credit losses	158,282	185,449	97,701
Noninterest income	77,539	72,781	78,202
Noninterest expense	(109,906)	(100,932)	(79,961)
Income before provision for income taxes	125,915	157,298	95,942
(Provision) benefit for income taxes	(30,158)	(37,525)	(21,951)
Net income	95,757	119,773	73,991
Total assets	6,850,638	5,972,567	6,526,863
Treasury and Other
Selected business segment financial information
Net interest income (expense)	20,193	(18,094)	8,967
Benefit (Provision) for credit losses	(3,513)	281	(15,078)
Net interest income after provision for credit losses	16,680	(17,813)	(6,111)
Noninterest income	7,901	20,463	21,152
Noninterest expense	(37,002)	(56,598)	(54,735)
Income before provision for income taxes	(12,421)	(53,948)	(39,694)
(Provision) benefit for income taxes	2,709	12,974	7,806
Net income	(9,712)	(40,974)	(31,888)
Total assets	$ 10,263,583	$ 11,871,467	$ 9,241,366