Loans and Leases - Aging Analysis of Past Due Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	$ 4,837,735	$ 4,672,909
Less: unearned income and deferred costs and fees	(3,796)	(3,789)
Total originated loans and leases, net of unearned income and deferred costs and fees	4,833,939	4,669,120
Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	1,077,635	1,091,651
Commercial and industrial | Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	107,494	108,608
Commercial and industrial | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	970,141	983,043
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	2,340,661	2,200,727
Commercial real estate | Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	170,229	129,959
Commercial real estate | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	2,004,763	1,866,802
Commercial real estate | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	165,669	203,966
Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	1,333,894	1,302,941
Residential real estate | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	229,608	241,256
Residential real estate | Mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	1,104,286	1,061,685
Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	70,989	63,123
Consumer and other | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	58,326	50,979
Consumer and other | Indirect
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	12,663	12,144
Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	14,556	14,467
Originated Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	4,556,048	4,349,180
Total Loans	4,572,537	4,362,332
90 days and accruing	0	44
Nonaccrual	19,340	16,253
Less: unearned income and deferred costs and fees	(3,796)	(3,789)
Less: unearned income and deferred costs and fees, current	(3,796)	(3,789)
Less: unearned income and deferred costs and fees, 90 days and accruing	0	0
Less: unearned income and deferred costs and fees, nonaccrual	0	0
Total originated loans and leases, net of unearned income and deferred costs and fees	4,568,741	4,358,543
Total originated loans and leases, net of unearned income and deferred costs and fees, current	4,552,252	4,345,391
Originated Loans and Leases | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	7,838	6,791
Less: unearned income and deferred costs and fees	0	0
Total originated loans and leases, net of unearned income and deferred costs and fees	7,838	6,791
Originated Loans and Leases | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	8,651	6,361
Less: unearned income and deferred costs and fees	0	0
Total originated loans and leases, net of unearned income and deferred costs and fees	8,651	6,361
Originated Loans and Leases | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	1,029,897	1,039,395
Total Loans	1,033,923	1,040,675
90 days and accruing	0	0
Nonaccrual	1,861	2,852
Originated Loans and Leases | Commercial and industrial | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	2,367	431
Originated Loans and Leases | Commercial and industrial | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	1,659	849
Originated Loans and Leases | Commercial and industrial | Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	107,494	108,608
Total Loans	107,494	108,608
90 days and accruing	0	0
Nonaccrual	0	0
Originated Loans and Leases | Commercial and industrial | Agriculture | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Originated Loans and Leases | Commercial and industrial | Agriculture | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Originated Loans and Leases | Commercial and industrial | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	922,403	930,787
Total Loans	926,429	932,067
90 days and accruing	0	0
Nonaccrual	1,861	2,852
Originated Loans and Leases | Commercial and industrial | Other | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	2,367	431
Originated Loans and Leases | Commercial and industrial | Other | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	1,659	849
Originated Loans and Leases | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	2,158,441	1,989,272
Total Loans	2,161,569	1,992,980
90 days and accruing	0	0
Nonaccrual	7,691	5,402
Originated Loans and Leases | Commercial real estate | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	1,272	1,583
Originated Loans and Leases | Commercial real estate | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	1,856	2,125
Originated Loans and Leases | Commercial real estate | Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	169,934	129,712
Total Loans	170,005	129,712
90 days and accruing	0	0
Nonaccrual	0	0
Originated Loans and Leases | Commercial real estate | Agriculture | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	71	0
Originated Loans and Leases | Commercial real estate | Agriculture | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Originated Loans and Leases | Commercial real estate | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	1,824,222	1,657,074
Total Loans	1,827,279	1,660,782
90 days and accruing	0	0
Nonaccrual	7,691	5,402
Originated Loans and Leases | Commercial real estate | Other | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	1,201	1,583
Originated Loans and Leases | Commercial real estate | Other | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	1,856	2,125
Originated Loans and Leases | Commercial real estate | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	164,285	202,486
Total Loans	164,285	202,486
90 days and accruing	0	0
Nonaccrual	0	0
Originated Loans and Leases | Commercial real estate | Construction | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Originated Loans and Leases | Commercial real estate | Construction | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Originated Loans and Leases | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	1,283,529	1,244,514
Total Loans	1,292,261	1,251,852
90 days and accruing	0	0
Nonaccrual	9,554	7,645
Originated Loans and Leases | Residential real estate | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	3,679	4,198
Originated Loans and Leases | Residential real estate | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	5,053	3,140
Originated Loans and Leases | Residential real estate | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	206,447	211,319
Total Loans	208,459	212,812
90 days and accruing	0	0
Nonaccrual	1,784	1,537
Originated Loans and Leases | Residential real estate | Home equity | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	986	1,045
Originated Loans and Leases | Residential real estate | Home equity | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	1,026	448
Originated Loans and Leases | Residential real estate | Mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	1,077,082	1,033,195
Total Loans	1,083,802	1,039,040
90 days and accruing	0	0
Nonaccrual	7,770	6,108
Originated Loans and Leases | Residential real estate | Mortgages | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	2,693	3,153
Originated Loans and Leases | Residential real estate | Mortgages | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	4,027	2,692
Originated Loans and Leases | Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	69,625	61,532
Total Loans	70,228	62,358
90 days and accruing	0	44
Nonaccrual	234	354
Originated Loans and Leases | Consumer and other | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	520	579
Originated Loans and Leases | Consumer and other | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	83	247
Originated Loans and Leases | Consumer and other | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	57,354	50,042
Total Loans	57,565	50,214
90 days and accruing	0	38
Nonaccrual	79	76
Originated Loans and Leases | Consumer and other | Other | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	187	130
Originated Loans and Leases | Consumer and other | Other | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	24	42
Originated Loans and Leases | Consumer and other | Indirect
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	12,271	11,490
Total Loans	12,663	12,144
90 days and accruing	0	6
Nonaccrual	155	278
Originated Loans and Leases | Consumer and other | Indirect | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	333	449
Originated Loans and Leases | Consumer and other | Indirect | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	59	205
Originated Loans and Leases | Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	14,556	14,467
Total Loans	14,556	14,467
90 days and accruing	0	0
Nonaccrual	0	0
Originated Loans and Leases | Leases | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Originated Loans and Leases | Leases | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Acquired Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	262,510	307,027
Total Loans	265,198	310,577
90 days and accruing	1,316	1,146
Nonaccrual	2,856	3,264
Less: unearned income and deferred costs and fees	0	0
Total originated loans and leases, net of unearned income and deferred costs and fees	265,198	310,577
Acquired Loans and Leases | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	67	1,256
Acquired Loans and Leases | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	2,621	2,294
Acquired Loans and Leases | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	43,702	50,903
Total Loans	43,712	50,976
90 days and accruing	10	61
Nonaccrual	22	0
Acquired Loans and Leases | Commercial and industrial | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	12
Acquired Loans and Leases | Commercial and industrial | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	10	61
Acquired Loans and Leases | Commercial and industrial | Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	0	0
Acquired Loans and Leases | Commercial and industrial | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	43,702	50,903
Total Loans	43,712	50,976
90 days and accruing	10	61
Nonaccrual	22	0
Acquired Loans and Leases | Commercial and industrial | Other | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	12
Acquired Loans and Leases | Commercial and industrial | Other | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	10	61
Acquired Loans and Leases | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	178,253	206,853
Total Loans	179,092	207,747
90 days and accruing	525	515
Nonaccrual	316	546
Acquired Loans and Leases | Commercial real estate | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	167
Acquired Loans and Leases | Commercial real estate | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	839	727
Acquired Loans and Leases | Commercial real estate | Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	224	247
Total Loans	224	247
90 days and accruing	0	0
Nonaccrual	0	0
Acquired Loans and Leases | Commercial real estate | Agriculture | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Acquired Loans and Leases | Commercial real estate | Agriculture | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Acquired Loans and Leases | Commercial real estate | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	176,645	205,126
Total Loans	177,484	206,020
90 days and accruing	525	515
Nonaccrual	316	546
Acquired Loans and Leases | Commercial real estate | Other | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	167
Acquired Loans and Leases | Commercial real estate | Other | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	839	727
Acquired Loans and Leases | Commercial real estate | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	1,384	1,480
Total Loans	1,384	1,480
90 days and accruing	0	0
Nonaccrual	0	0
Acquired Loans and Leases | Commercial real estate | Construction | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Acquired Loans and Leases | Commercial real estate | Construction | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Acquired Loans and Leases | Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	39,797	48,510
Total Loans	41,633	51,089
90 days and accruing	781	570
Nonaccrual	2,518	2,718
Acquired Loans and Leases | Residential real estate | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	64	1,073
Acquired Loans and Leases | Residential real estate | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	1,772	1,506
Acquired Loans and Leases | Residential real estate | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	20,300	27,279
Total Loans	21,149	28,444
90 days and accruing	59	130
Nonaccrual	1,414	1,604
Acquired Loans and Leases | Residential real estate | Home equity | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	46	601
Acquired Loans and Leases | Residential real estate | Home equity | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	803	564
Acquired Loans and Leases | Residential real estate | Mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	19,497	21,231
Total Loans	20,484	22,645
90 days and accruing	722	440
Nonaccrual	1,104	1,114
Acquired Loans and Leases | Residential real estate | Mortgages | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	18	472
Acquired Loans and Leases | Residential real estate | Mortgages | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	969	942
Acquired Loans and Leases | Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	758	761
Total Loans	761	765
90 days and accruing	0	0
Nonaccrual	0	0
Acquired Loans and Leases | Consumer and other | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	3	4
Acquired Loans and Leases | Consumer and other | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Acquired Loans and Leases | Consumer and other | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	758	761
Total Loans	761	765
90 days and accruing	0	0
Nonaccrual	0	0
Acquired Loans and Leases | Consumer and other | Other | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	3	4
Acquired Loans and Leases | Consumer and other | Other | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Acquired Loans and Leases | Consumer and other | Indirect
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	0	0
Acquired Loans and Leases | Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	$ 0	$ 0