Reportable Operating Segments - Selected Business Segment Financial Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Selected business segment financial information
Net interest income (expense)	$ 167,247	$ 133,872
Provision (Benefit) for credit losses	(8,800)	5,747
Net interest income after (provision) benefit for credit losses	158,447	139,619
Noninterest income	49,023	41,380
Noninterest expense	(118,567)	(104,042)
Income before provision for income taxes	88,903	76,957
(Provision) benefit for income taxes	(22,085)	(19,238)
Net income	66,818	57,719
Total assets	24,884,207		$ 24,577,223
Retail Banking
Selected business segment financial information
Net interest income (expense)	108,920	94,048
Provision (Benefit) for credit losses	(2,563)	1,841
Net interest income after (provision) benefit for credit losses	106,357	95,889
Noninterest income	24,267	23,315
Noninterest expense	(75,843)	(70,220)
Income before provision for income taxes	54,781	48,984
(Provision) benefit for income taxes	(13,266)	(12,150)
Net income	41,515	36,834
Commercial Banking
Selected business segment financial information
Net interest income (expense)	40,939	35,088
Provision (Benefit) for credit losses	(3,873)	2,542
Net interest income after (provision) benefit for credit losses	37,066	37,630
Noninterest income	17,888	18,655
Noninterest expense	(27,770)	(26,505)
Income before provision for income taxes	27,184	29,780
(Provision) benefit for income taxes	(6,330)	(7,253)
Net income	20,854	22,527
Treasury and Other
Selected business segment financial information
Net interest income (expense)	17,388	4,736
Provision (Benefit) for credit losses	(2,364)	1,364
Net interest income after (provision) benefit for credit losses	15,024	6,100
Noninterest income	6,868	(590)
Noninterest expense	(14,954)	(7,317)
Income before provision for income taxes	6,938	(1,807)
(Provision) benefit for income taxes	(2,489)	165
Net income	$ 4,449	$ (1,642)