Loans and Leases - Schedule of Loans and Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 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
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,091,651	1,044,619
Commercial and industrial | Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	108,608	118,247
Commercial and industrial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	983,043	926,372
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	2,200,727	1,920,841
Commercial real estate | Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	129,959	102,776
Commercial real estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	203,966	144,770
Commercial real estate | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,866,802	1,673,295
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,302,941	1,219,815
Residential real estate | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	241,256	247,014
Residential real estate | Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,061,685	972,801
Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	63,123	60,054
Consumer and other | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	50,979	45,219
Consumer and other | Indirect
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	12,144	14,835
Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	14,467	16,650
Originated Loans and Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	4,362,332	3,867,868
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	4,358,543	3,863,922
Originated Loans and Leases | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,040,675	965,302
Originated Loans and Leases | Commercial and industrial | Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	108,608	118,247
Originated Loans and Leases | Commercial and industrial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	932,067	847,055
Originated Loans and Leases | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,992,980	1,670,033
Originated Loans and Leases | Commercial real estate | Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	129,712	102,509
Originated Loans and Leases | Commercial real estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	202,486	135,834
Originated Loans and Leases | Commercial real estate | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,660,782	1,431,690
Originated Loans and Leases | Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,251,852	1,156,655
Originated Loans and Leases | Residential real estate | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	212,812	209,277
Originated Loans and Leases | Residential real estate | Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,039,040	947,378
Originated Loans and Leases | Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	62,358	59,228
Originated Loans and Leases | Consumer and other | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	50,214	44,393
Originated Loans and Leases | Consumer and other | Indirect
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	12,144	14,835
Originated Loans and Leases | Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	14,467	16,650
Acquired Loans and Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	310,577	394,111
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 | Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	50,976	79,317
Acquired Loans and Leases | Commercial and industrial | Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0	0
Acquired Loans and Leases | Commercial and industrial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	50,976	79,317
Acquired Loans and Leases | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	207,747	250,808
Acquired Loans and Leases | Commercial real estate | Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	247	267
Acquired Loans and Leases | Commercial real estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,480	8,936
Acquired Loans and Leases | Commercial real estate | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	206,020	241,605
Acquired Loans and Leases | Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	51,089	63,160
Acquired Loans and Leases | Residential real estate | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	28,444	37,737
Acquired Loans and Leases | Residential real estate | Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	22,645	25,423
Acquired Loans and Leases | Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	765	826
Acquired Loans and Leases | Consumer and other | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	765	826
Acquired Loans and Leases | Consumer and other | Indirect
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 0	0
Acquired Loans and Leases | Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases