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Amount of credit loss expense (reversal of expense) for financing receivable.

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Loans (Allowance for Credit Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Allowance for Credit Losses [Roll Forward]
Beginning Balance	$ 36,641	$ 16,243	$ 16,278	$ 15,823
Provision for credit loss expense	5,900	250	11,050	925
Initial allowance on loans purchased with credit deterioration			0
Loans charged-off	(200)	(398)	(768)	(799)
Recoveries collected	90	144	218	290
Ending Balance	42,431	16,239	42,431	16,239
Impact of adopting ASC 326 - PCD Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance			405
Impact of ASC 326 Adoption \| Impact of adopting ASC 326
Allowance for Credit Losses [Roll Forward]
Beginning Balance			8,767
Impact of ASC 326 Adoption \| Impact of adopting ASC 326 - PCD Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance			6,886
Commercial and Industrial Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance	8,814		4,799
Provision for credit loss expense	(31)		(166)
Initial allowance on loans purchased with credit deterioration			0
Loans charged-off	0		(296)
Recoveries collected	4		14
Ending Balance	8,787		8,787
Commercial and Industrial Loans \| Impact of ASC 326 Adoption \| Impact of adopting ASC 326
Allowance for Credit Losses [Roll Forward]
Beginning Balance			2,245
Commercial and Industrial Loans \| Impact of ASC 326 Adoption \| Impact of adopting ASC 326 - PCD Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance			2,191
Commercial Real Estate Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance	17,310	5,741	4,692	5,291
Provision for credit loss expense	5,049	104	10,215	669
Initial allowance on loans purchased with credit deterioration			0
Loans charged-off	0	(18)	0	(138)
Recoveries collected	10	14	14	19
Ending Balance	22,369	5,841	22,369	5,841
Commercial Real Estate Loans \| Impact of adopting ASC 326 - PCD Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance			400
Commercial Real Estate Loans \| Impact of ASC 326 Adoption \| Impact of adopting ASC 326
Allowance for Credit Losses [Roll Forward]
Beginning Balance			3,063
Commercial Real Estate Loans \| Impact of ASC 326 Adoption \| Impact of adopting ASC 326 - PCD Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance			4,385
Agricultural Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance	6,485	5,453	5,315	5,776
Provision for credit loss expense	545	272	149	(51)
Initial allowance on loans purchased with credit deterioration			0
Loans charged-off	0	0	0	0
Recoveries collected	0	0	0	0
Ending Balance	7,030	5,725	7,030	5,725
Agricultural Loans \| Impact of adopting ASC 326 - PCD Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance			0
Agricultural Loans \| Impact of ASC 326 Adoption \| Impact of adopting ASC 326
Allowance for Credit Losses [Roll Forward]
Beginning Balance			1,438
Agricultural Loans \| Impact of ASC 326 Adoption \| Impact of adopting ASC 326 - PCD Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance			128
Leases
Allowance for Credit Losses [Roll Forward]
Beginning Balance	172		0
Provision for credit loss expense	30		97
Initial allowance on loans purchased with credit deterioration			0
Loans charged-off	0		0
Recoveries collected	0		0
Ending Balance	202		202
Leases \| Impact of ASC 326 Adoption \| Impact of adopting ASC 326
Allowance for Credit Losses [Roll Forward]
Beginning Balance			105
Leases \| Impact of ASC 326 Adoption \| Impact of adopting ASC 326 - PCD Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance			0
Consumer Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance	455	483	434	420
Provision for credit loss expense	109	124	314	333
Initial allowance on loans purchased with credit deterioration			0
Loans charged-off	(144)	(278)	(381)	(545)
Recoveries collected	76	93	188	214
Ending Balance	496	422	496	422
Consumer Loans \| Impact of adopting ASC 326 - PCD Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance			0
Consumer Loans \| Impact of ASC 326 Adoption \| Impact of adopting ASC 326
Allowance for Credit Losses [Roll Forward]
Beginning Balance			(59)
Consumer Loans \| Impact of ASC 326 Adoption \| Impact of adopting ASC 326 - PCD Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance			0
Home Equity Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance	977	214	200	229
Provision for credit loss expense	85	54	65	39
Initial allowance on loans purchased with credit deterioration			0
Loans charged-off	0	(10)	0	(10)
Recoveries collected	0	0	0	0
Ending Balance	1,062	258	1,062	258
Home Equity Loans \| Impact of adopting ASC 326 - PCD Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance			0
Home Equity Loans \| Impact of ASC 326 Adoption \| Impact of adopting ASC 326
Allowance for Credit Losses [Roll Forward]
Beginning Balance			762
Home Equity Loans \| Impact of ASC 326 Adoption \| Impact of adopting ASC 326 - PCD Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance			35
Credit Cards
Allowance for Credit Losses [Roll Forward]
Beginning Balance	124		0
Provision for credit loss expense	26		60
Initial allowance on loans purchased with credit deterioration			0
Loans charged-off	(25)		(60)
Recoveries collected	0		1
Ending Balance	125		125
Credit Cards \| Impact of ASC 326 Adoption \| Impact of adopting ASC 326
Allowance for Credit Losses [Roll Forward]
Beginning Balance			124
Credit Cards \| Impact of ASC 326 Adoption \| Impact of adopting ASC 326 - PCD Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance			0
Residential Mortgage Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance	2,304	429	333	472
Provision for credit loss expense	87	(47)	316	(79)
Initial allowance on loans purchased with credit deterioration			0
Loans charged-off	(31)	(36)	(31)	(50)
Recoveries collected	0	3	1	6
Ending Balance	2,360	349	2,360	349
Residential Mortgage Loans \| Impact of adopting ASC 326 - PCD Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance			5
Residential Mortgage Loans \| Impact of ASC 326 Adoption \| Impact of adopting ASC 326
Allowance for Credit Losses [Roll Forward]
Beginning Balance			1,594
Residential Mortgage Loans \| Impact of ASC 326 Adoption \| Impact of adopting ASC 326 - PCD Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance			147
Unallocated
Allowance for Credit Losses [Roll Forward]
Beginning Balance	0	606	505	682
Provision for credit loss expense	0	46	0	(30)
Initial allowance on loans purchased with credit deterioration			0
Loans charged-off	0	0	0	0
Recoveries collected	0	0	0	0
Ending Balance	$ 0	$ 652	0	$ 652
Unallocated \| Impact of adopting ASC 326 - PCD Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance			0
Unallocated \| Impact of ASC 326 Adoption \| Impact of adopting ASC 326
Allowance for Credit Losses [Roll Forward]
Beginning Balance			(505)
Unallocated \| Impact of ASC 326 Adoption \| Impact of adopting ASC 326 - PCD Loans
Allowance for Credit Losses [Roll Forward]
Beginning Balance			$ 0