Segment Reporting - Financial Information for Operating Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Financial information for the Company's operating segments
Net interest income (loss)	$ 135,775	$ 99,629
Provision for credit losses	7,960	1,500
Noninterest income (loss)	37,293	37,458
Noninterest expense	107,708	94,105
Income (loss) before income taxes	57,400	41,482
Income tax expense (benefit)	11,322	7,935
Net income (loss)	46,078	33,547
Total assets	17,474,083	16,863,757	$ 16,988,176
Goodwill	991,665	946,291	991,708
Community Banks
Financial information for the Company's operating segments
Goodwill	988,898		988,941
Insurance
Financial information for the Company's operating segments
Goodwill	2,767		$ 2,767
Operating segments | Community Banks
Financial information for the Company's operating segments
Net interest income (loss)	140,757	103,932
Provision for credit losses	7,960	1,500
Noninterest income (loss)	28,493	28,306
Noninterest expense	100,381	86,871
Income (loss) before income taxes	60,909	43,867
Income tax expense (benefit)	12,722	9,131
Net income (loss)	48,187	34,736
Total assets	17,362,799	16,757,670
Goodwill	988,898	943,524
Operating segments | Insurance
Financial information for the Company's operating segments
Net interest income (loss)	286	93
Provision for credit losses	0	0
Noninterest income (loss)	3,362	3,097
Noninterest expense	2,039	2,116
Income (loss) before income taxes	1,609	1,074
Income tax expense (benefit)	416	281
Net income (loss)	1,193	793
Total assets	37,168	33,794
Goodwill	2,767	2,767
Operating segments | Wealth Management
Financial information for the Company's operating segments
Net interest income (loss)	1,050	490
Provision for credit losses	0	0
Noninterest income (loss)	5,812	6,505
Noninterest expense	4,928	4,755
Income (loss) before income taxes	1,934	2,240
Income tax expense (benefit)	4	0
Net income (loss)	1,930	2,240
Total assets	79,452	64,761
Goodwill	0	0
Other
Financial information for the Company's operating segments
Net interest income (loss)	(6,318)	(4,886)
Provision for credit losses	0	0
Noninterest income (loss)	(374)	(450)
Noninterest expense	360	363
Income (loss) before income taxes	(7,052)	(5,699)
Income tax expense (benefit)	(1,820)	(1,477)
Net income (loss)	(5,232)	(4,222)
Total assets	(5,336)	7,532
Goodwill	$ 0	$ 0