Loans (Allowance for Loan Losses and Recorded Investment in Loans) (Details) - USD ($) $ in Thousands		Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Allowance for Loan Losses:
Individually Evaluated for Impairment				$ 2,971
Collectively Evaluated for Impairment				12,902
Total Ending Allowance Balance		$ 36,641	$ 31,931	16,278	$ 16,243	$ 15,823
Loans:
Loans Individually Evaluated for Impairment				6,269
Loans Collectively Evaluated for Impairment				3,076,835
Financing Receivable And Accrued Interest, Before Allowance For Credit Loss And Fee	[1]			3,095,902
Accrued interest included in recorded investment		12,350		13,929
Acquired with Deteriorated Credit Quality
Allowance for Loan Losses:
Total Ending Allowance Balance				405
Loans:
Financing Receivable And Accrued Interest, Before Allowance For Credit Loss And Fee				12,798
Commercial and Industrial Loans and Leases
Allowance for Loan Losses:
Individually Evaluated for Impairment				2,412
Collectively Evaluated for Impairment				2,387
Total Ending Allowance Balance				4,799	3,317	2,953
Loans:
Loans Individually Evaluated for Impairment				4,707
Loans Collectively Evaluated for Impairment				585,328
Financing Receivable And Accrued Interest, Before Allowance For Credit Loss And Fee	[1]			591,403
Commercial and Industrial Loans and Leases | Acquired with Deteriorated Credit Quality
Allowance for Loan Losses:
Total Ending Allowance Balance				0
Loans:
Financing Receivable And Accrued Interest, Before Allowance For Credit Loss And Fee				1,368
Commercial Real Estate Loans
Allowance for Loan Losses:
Individually Evaluated for Impairment				559
Collectively Evaluated for Impairment				3,733
Total Ending Allowance Balance		17,310		4,692	5,741	5,291
Loans:
Loans Individually Evaluated for Impairment				1,562
Loans Collectively Evaluated for Impairment				1,491,090
Financing Receivable And Accrued Interest, Before Allowance For Credit Loss And Fee	[1]			1,499,864
Commercial Real Estate Loans | Acquired with Deteriorated Credit Quality
Allowance for Loan Losses:
Total Ending Allowance Balance				400
Loans:
Financing Receivable And Accrued Interest, Before Allowance For Credit Loss And Fee				7,212
Agricultural Loans
Allowance for Loan Losses:
Individually Evaluated for Impairment				0
Collectively Evaluated for Impairment				5,315
Total Ending Allowance Balance		6,485		5,315	5,453	5,776
Loans:
Loans Individually Evaluated for Impairment				0
Loans Collectively Evaluated for Impairment				387,710
Financing Receivable And Accrued Interest, Before Allowance For Credit Loss And Fee	[1]			390,871
Agricultural Loans | Acquired with Deteriorated Credit Quality
Allowance for Loan Losses:
Total Ending Allowance Balance				0
Loans:
Financing Receivable And Accrued Interest, Before Allowance For Credit Loss And Fee				3,161
Home Equity Loans
Allowance for Loan Losses:
Individually Evaluated for Impairment				0
Collectively Evaluated for Impairment				200
Total Ending Allowance Balance		977		200	214	229
Loans:
Loans Individually Evaluated for Impairment				0
Loans Collectively Evaluated for Impairment				226,406
Financing Receivable And Accrued Interest, Before Allowance For Credit Loss And Fee	[1]			226,775
Home Equity Loans | Acquired with Deteriorated Credit Quality
Allowance for Loan Losses:
Total Ending Allowance Balance				0
Loans:
Financing Receivable And Accrued Interest, Before Allowance For Credit Loss And Fee				369
Consumer Loans
Allowance for Loan Losses:
Individually Evaluated for Impairment				0
Collectively Evaluated for Impairment				434
Total Ending Allowance Balance		455		434	483	420
Loans:
Loans Individually Evaluated for Impairment				0
Loans Collectively Evaluated for Impairment				81,429
Financing Receivable And Accrued Interest, Before Allowance For Credit Loss And Fee	[1]			81,429
Consumer Loans | Acquired with Deteriorated Credit Quality
Allowance for Loan Losses:
Total Ending Allowance Balance				0
Residential Mortgage Loans
Allowance for Loan Losses:
Individually Evaluated for Impairment				0
Collectively Evaluated for Impairment				328
Total Ending Allowance Balance		2,304		333	429	472
Loans:
Loans Individually Evaluated for Impairment				0
Loans Collectively Evaluated for Impairment				304,872
Financing Receivable And Accrued Interest, Before Allowance For Credit Loss And Fee	[1]			305,560
Residential Mortgage Loans | Acquired with Deteriorated Credit Quality
Allowance for Loan Losses:
Total Ending Allowance Balance				5
Loans:
Financing Receivable And Accrued Interest, Before Allowance For Credit Loss And Fee				688
Unallocated
Allowance for Loan Losses:
Individually Evaluated for Impairment				0
Collectively Evaluated for Impairment				505
Total Ending Allowance Balance		$ 0		505	$ 606	$ 682
Unallocated | Acquired with Deteriorated Credit Quality
Allowance for Loan Losses:
Total Ending Allowance Balance				$ 0

[1] Total recorded investment in loans includes $13,929 in accrued interest.