Loans - Allowance for Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Allowance for Credit Losses [Roll Forward]
Beginning Balance	$ 76,105	$ 43,946	$ 44,436	$ 43,765	$ 43,765
Change in Accounting Method			(7)
2/1/2025 Acquired Heartland PCD			16,503
Day 2 CECL Provision - Heartland			16,200
Provision (Benefit) for Credit Loss Expense	700	625	1,007	2,150
Loans Charged-off	(1,126)	(619)	(2,772)	(2,279)
Recoveries Collected	378	172	690	488
Total Ending Allowance Balance	76,057	44,124	76,057	44,124	44,436
Commercial and Industrial Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance	17,739	7,200	7,059	7,921	7,921
Change in Accounting Method			1,438
2/1/2025 Acquired Heartland PCD			5,246
Day 2 CECL Provision - Heartland			1,797
Provision (Benefit) for Credit Loss Expense	272	(137)	2,817	(768)
Loans Charged-off	(384)	(92)	(757)	(223)	(223)
Recoveries Collected	6	3	33	44
Total Ending Allowance Balance	17,633	6,974	17,633	6,974	7,059
Commercial Real Estate Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance	38,803	26,598	25,818	25,923	25,923
Change in Accounting Method			(3,271)
2/1/2025 Acquired Heartland PCD			7,675
Day 2 CECL Provision - Heartland			7,522
Provision (Benefit) for Credit Loss Expense	329	54	1,414	1,028
Loans Charged-off	0	0	(26)	(308)	(308)
Recoveries Collected	0	4	0	13
Total Ending Allowance Balance	39,132	26,656	39,132	26,656	25,818
Agricultural Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance	3,130	3,697	4,917	3,837	3,837
Change in Accounting Method			(1,655)
2/1/2025 Acquired Heartland PCD			3,352
Day 2 CECL Provision - Heartland			170
Provision (Benefit) for Credit Loss Expense	98	211	(3,556)	70
Loans Charged-off	0	(7)	0	(8)	(8)
Recoveries Collected	0	0	0	2
Total Ending Allowance Balance	3,228	3,901	3,228	3,901	4,917
Leases
Allowance for Credit Losses [Roll Forward]
Beginning Balance	1,192	368	397	346	346
Change in Accounting Method			720
2/1/2025 Acquired Heartland PCD			0
Day 2 CECL Provision - Heartland			0
Provision (Benefit) for Credit Loss Expense	(16)	28	59	50
Loans Charged-off	0	0	0	0	0
Recoveries Collected	0	0	0	0
Total Ending Allowance Balance	1,176	396	1,176	396	397
Consumer Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance	691	722	727	759	759
Change in Accounting Method			(284)
2/1/2025 Acquired Heartland PCD			20
Day 2 CECL Provision - Heartland			179
Provision (Benefit) for Credit Loss Expense	303	224	789	700
Loans Charged-off	(446)	(364)	(1,105)	(1,117)	(1,511)
Recoveries Collected	138	158	360	398
Total Ending Allowance Balance	686	740	686	740	727
Home Equity Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance	4,334	2,058	2,196	1,834	1,834
Change in Accounting Method			1,056
2/1/2025 Acquired Heartland PCD			11
Day 2 CECL Provision - Heartland			570
Provision (Benefit) for Credit Loss Expense	46	72	538	421
Loans Charged-off	(71)	0	(71)	(134)	(170)
Recoveries Collected	5	0	14	9
Total Ending Allowance Balance	4,314	2,130	4,314	2,130	2,196
Credit Cards
Allowance for Credit Losses [Roll Forward]
Beginning Balance	621	413	520	383	383
Change in Accounting Method			(24)
2/1/2025 Acquired Heartland PCD			0
Day 2 CECL Provision - Heartland			0
Provision (Benefit) for Credit Loss Expense	26	202	657	550
Loans Charged-off	(182)	(156)	(742)	(489)
Recoveries Collected	208	7	262	22
Total Ending Allowance Balance	673	466	673	466	520
Residential Mortgage Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance	9,595	2,890	2,802	2,762	2,762
Change in Accounting Method			2,013
2/1/2025 Acquired Heartland PCD			199
Day 2 CECL Provision - Heartland			5,962
Provision (Benefit) for Credit Loss Expense	(358)	(29)	(1,711)	99
Loans Charged-off	(43)	0	(71)	0	0
Recoveries Collected	21	0	21	0
Total Ending Allowance Balance	$ 9,215	$ 2,861	$ 9,215	$ 2,861	$ 2,802