Loans and Leases - Aging Analysis of Past Due Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	$ 4,672,909	$ 4,261,979
Less: unearned income and deferred costs and fees	(3,789)	(3,946)
Total originated loans and leases, net of unearned income and deferred costs and fees	4,669,120	4,258,033
Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	1,091,651	1,044,619
Commercial and industrial | Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	108,608	118,247
Commercial and industrial | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	983,043	926,372
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	2,200,727	1,920,841
Commercial real estate | Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	129,959	102,776
Commercial real estate | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	1,866,802	1,673,295
Commercial real estate | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	203,966	144,770
Residential real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	1,302,941	1,219,815
Residential real estate | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	241,256	247,014
Residential real estate | Mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	1,061,685	972,801
Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	63,123	60,054
Consumer and other | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	50,979	45,219
Consumer and other | Indirect
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	12,144	14,835
Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Loans	14,467	16,650
Originated Loans and Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	4,349,180	3,852,240
Total Loans	4,362,332	3,867,868
90 days and accruing	44	0
Nonaccrual	16,253	14,300
Less: unearned income and deferred costs and fees	(3,789)	(3,946)
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
Less: unearned income and deferred costs and fees, current	(3,789)	(3,946)
Total originated loans and leases, net of unearned income and deferred costs and fees	4,358,543	3,863,922
Total originated loans and leases, net of unearned income and deferred costs and fees, current	4,345,391	3,848,294
Originated Loans and Leases | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	6,791	6,694
Less: unearned income and deferred costs and fees	0	0
Total originated loans and leases, net of unearned income and deferred costs and fees	6,791	6,694
Originated Loans and Leases | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	6,361	8,934
Less: unearned income and deferred costs and fees	0	0
Total originated loans and leases, net of unearned income and deferred costs and fees	6,361	8,934
Originated Loans and Leases | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	1,039,395	963,709
Total Loans	1,040,675	965,302
90 days and accruing	0	0
Nonaccrual	2,852	526
Originated Loans and Leases | Commercial and industrial | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	431	1,312
Originated Loans and Leases | Commercial and industrial | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	849	281
Originated Loans and Leases | Commercial and industrial | Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	108,608	118,247
Total Loans	108,608	118,247
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	930,787	845,462
Total Loans	932,067	847,055
90 days and accruing	0	0
Nonaccrual	2,852	526
Originated Loans and Leases | Commercial and industrial | Other | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	431	1,312
Originated Loans and Leases | Commercial and industrial | Other | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	849	281
Originated Loans and Leases | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	1,989,272	1,664,399
Total Loans	1,992,980	1,670,033
90 days and accruing	0	0
Nonaccrual	5,402	6,150
Originated Loans and Leases | Commercial real estate | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	1,583	2,563
Originated Loans and Leases | Commercial real estate | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	2,125	3,071
Originated Loans and Leases | Commercial real estate | Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	129,712	102,492
Total Loans	129,712	102,509
90 days and accruing	0	0
Nonaccrual	0	162
Originated Loans and Leases | Commercial real estate | Agriculture | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	17
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	1,657,074	1,426,073
Total Loans	1,660,782	1,431,690
90 days and accruing	0	0
Nonaccrual	5,402	5,988
Originated Loans and Leases | Commercial real estate | Other | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	1,583	2,546
Originated Loans and Leases | Commercial real estate | Other | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	2,125	3,071
Originated Loans and Leases | Commercial real estate | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	202,486	135,834
Total Loans	202,486	135,834
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	1,244,514	1,149,275
Total Loans	1,251,852	1,156,655
90 days and accruing	0	0
Nonaccrual	7,645	7,458
Originated Loans and Leases | Residential real estate | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	4,198	2,182
Originated Loans and Leases | Residential real estate | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	3,140	5,198
Originated Loans and Leases | Residential real estate | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	211,319	206,890
Total Loans	212,812	209,277
90 days and accruing	0	0
Nonaccrual	1,537	2,016
Originated Loans and Leases | Residential real estate | Home equity | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	1,045	433
Originated Loans and Leases | Residential real estate | Home equity | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	448	1,954
Originated Loans and Leases | Residential real estate | Mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	1,033,195	942,385
Total Loans	1,039,040	947,378
90 days and accruing	0	0
Nonaccrual	6,108	5,442
Originated Loans and Leases | Residential real estate | Mortgages | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	3,153	1,749
Originated Loans and Leases | Residential real estate | Mortgages | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	2,692	3,244
Originated Loans and Leases | Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	61,532	58,207
Total Loans	62,358	59,228
90 days and accruing	44	0
Nonaccrual	354	166
Originated Loans and Leases | Consumer and other | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	579	637
Originated Loans and Leases | Consumer and other | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	247	384
Originated Loans and Leases | Consumer and other | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	50,042	44,192
Total Loans	50,214	44,393
90 days and accruing	38	0
Nonaccrual	76	0
Originated Loans and Leases | Consumer and other | Other | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	130	193
Originated Loans and Leases | Consumer and other | Other | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	42	8
Originated Loans and Leases | Consumer and other | Indirect
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	11,490	14,015
Total Loans	12,144	14,835
90 days and accruing	6	0
Nonaccrual	278	166
Originated Loans and Leases | Consumer and other | Indirect | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	449	444
Originated Loans and Leases | Consumer and other | Indirect | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	205	376
Originated Loans and Leases | Leases
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	14,467	16,650
Total Loans	14,467	16,650
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	307,027	385,231
Total Loans	310,577	394,111
90 days and accruing	1,146	2,557
Nonaccrual	3,264	4,741
Less: unearned income and deferred costs and fees	0	0
Total originated loans and leases, net of unearned income and deferred costs and fees	310,577	394,111
Acquired Loans and Leases | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	1,256	2,553
Acquired Loans and Leases | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	2,294	6,327
Acquired Loans and Leases | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	50,903	79,218
Total Loans	50,976	79,317
90 days and accruing	61	40
Nonaccrual	0	212
Acquired Loans and Leases | Commercial and industrial | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	12	12
Acquired Loans and Leases | Commercial and industrial | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	61	87
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	50,903	79,218
Total Loans	50,976	79,317
90 days and accruing	61	40
Nonaccrual	0	212
Acquired Loans and Leases | Commercial and industrial | Other | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	12	12
Acquired Loans and Leases | Commercial and industrial | Other | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	61	87
Acquired Loans and Leases | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	206,853	245,395
Total Loans	207,747	250,808
90 days and accruing	515	1,402
Nonaccrual	546	2,926
Acquired Loans and Leases | Commercial real estate | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	167	1,461
Acquired Loans and Leases | Commercial real estate | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	727	3,952
Acquired Loans and Leases | Commercial real estate | Agriculture
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	247	267
Total Loans	247	267
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	205,126	236,192
Total Loans	206,020	241,605
90 days and accruing	515	1,402
Nonaccrual	546	2,926
Acquired Loans and Leases | Commercial real estate | Other | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	167	1,461
Acquired Loans and Leases | Commercial real estate | Other | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	727	3,952
Acquired Loans and Leases | Commercial real estate | Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	1,480	8,936
Total Loans	1,480	8,936
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	48,510	59,792
Total Loans	51,089	63,160
90 days and accruing	570	1,115
Nonaccrual	2,718	1,603
Acquired Loans and Leases | Residential real estate | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	1,073	1,080
Acquired Loans and Leases | Residential real estate | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	1,506	2,288
Acquired Loans and Leases | Residential real estate | Home equity
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	27,279	36,849
Total Loans	28,444	37,737
90 days and accruing	130	185
Nonaccrual	1,604	663
Acquired Loans and Leases | Residential real estate | Home equity | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	601	251
Acquired Loans and Leases | Residential real estate | Home equity | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	564	637
Acquired Loans and Leases | Residential real estate | Mortgages
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	21,231	22,943
Total Loans	22,645	25,423
90 days and accruing	440	930
Nonaccrual	1,114	940
Acquired Loans and Leases | Residential real estate | Mortgages | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	472	829
Acquired Loans and Leases | Residential real estate | Mortgages | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	942	1,651
Acquired Loans and Leases | Consumer and other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans	761	826
Total Loans	765	826
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	4	0
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	761	826
Total Loans	765	826
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	4	0
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
Acquired Loans and Leases | Covered loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current Loans		0
Total Loans	$ 0	0
90 days and accruing		0
Nonaccrual		0
Acquired Loans and Leases | Covered loans | 30-89 days
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due		0
Acquired Loans and Leases | Covered loans | 90 days or more
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due		$ 0