Loans (Schedule of Aging of Recorded Investment in Loans) (Details) - USD ($) $ in Thousands	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	$ 2,744,042	[1]	$ 2,154,502	[2]
Total Past Due	21,364	[1]	11,975	[2]
Loans Not Past Due	2,722,678	[1]	2,142,527	[2]
Accrued interest receivable included in total recorded investment in loans and leases	12,301		9,483
Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	545,342	[1]	488,058	[2]
Total Past Due	5,669		2,479
Loans Not Past Due	539,673		485,579
Commercial Real Estate Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	1,211,882	[1]	929,040	[2]
Total Past Due	4,505		3,556
Loans Not Past Due	1,207,377		925,484
Agricultural Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	370,694	[1]	337,801	[2]
Total Past Due	1,642		295
Loans Not Past Due	369,052		337,506
Home Equity Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	209,009	[1]	152,757	[2]
Total Past Due	656		658
Loans Not Past Due	208,353		152,099
Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	77,761	[1]	67,647	[2]
Total Past Due	1,214		629
Loans Not Past Due	76,547		67,018
Residential Mortgage Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	329,354	[1]	179,199	[2]
Total Past Due	7,678		4,358
Loans Not Past Due	321,676		174,841
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	12,958	[1]	4,927	[2]
30-59 Days Past Due | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	5,414		209
30-59 Days Past Due | Commercial Real Estate Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	768		1,229
30-59 Days Past Due | Agricultural Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	563		27
30-59 Days Past Due | Home Equity Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	471		366
30-59 Days Past Due | Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	971		246
30-59 Days Past Due | Residential Mortgage Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,771		2,850
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,432	[1]	4,452	[2]
60-89 Days Past Due | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	183		1,365
60-89 Days Past Due | Commercial Real Estate Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	705		1,650
60-89 Days Past Due | Agricultural Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	805		0
60-89 Days Past Due | Home Equity Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	125		93
60-89 Days Past Due | Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	94		97
60-89 Days Past Due | Residential Mortgage Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,520		1,247
90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	4,974	[1]	2,596	[2]
90 Days or More Past Due | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	72		905
90 Days or More Past Due | Commercial Real Estate Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,032		677
90 Days or More Past Due | Agricultural Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	274		268
90 Days or More Past Due | Home Equity Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	60		199
90 Days or More Past Due | Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	149		286
90 Days or More Past Due | Residential Mortgage Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,387		261
Loans Acquired with Deteriorated Credit Quality
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	11,556		9,117		$ 11,048
Total Past Due	2,592		443
Loans Not Past Due	8,964		8,674
Loans Acquired with Deteriorated Credit Quality | Commercial and Industrial Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	1,038		988		1,656
Loans Acquired with Deteriorated Credit Quality | Commercial Real Estate Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	6,993		6,452		7,688
Loans Acquired with Deteriorated Credit Quality | Agricultural Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	1,877		789		706
Loans Acquired with Deteriorated Credit Quality | Home Equity Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	365		0		0
Loans Acquired with Deteriorated Credit Quality | Consumer Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	0		0		53
Loans Acquired with Deteriorated Credit Quality | Residential Mortgage Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	1,283		888		$ 945
Loans Acquired with Deteriorated Credit Quality | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	448		342
Loans Acquired with Deteriorated Credit Quality | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	885		74
Loans Acquired with Deteriorated Credit Quality | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,259		$ 27
Loans Acquired with Deteriorated Credit Quality | Branch and Bank Acquisitions
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total	481,901
Total Past Due	6,382
Loans Not Past Due	475,519
Loans Acquired with Deteriorated Credit Quality | Branch and Bank Acquisitions | 30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,571
Loans Acquired with Deteriorated Credit Quality | Branch and Bank Acquisitions | 60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,620
Loans Acquired with Deteriorated Credit Quality | Branch and Bank Acquisitions | 90 Days or More Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 2,191

[1] Total recorded investment in loans includes $12,301 in accrued interest.

[2] Total recorded investment in loans includes $9,483 in accrued interest.