Loans and Leases - Schedule of Loans and Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 4,806,306	$ 4,672,909
Less: unearned income and deferred costs and fees	(3,597)	(3,789)
Total loans and leases, net of unearned income and deferred costs and fees	4,802,709	4,669,120
Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	4,534,838	4,362,332
Less: unearned income and deferred costs and fees	(3,597)	(3,789)
Total loans and leases, net of unearned income and deferred costs and fees	4,531,241	4,358,543
Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	271,468	310,577
Less: unearned income and deferred costs and fees	0	0
Total loans and leases, net of unearned income and deferred costs and fees	271,468	310,577
Commercial and industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,065,385	1,091,651
Commercial and industrial | Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	93,228	108,608
Commercial and industrial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	972,157	983,043
Commercial and industrial | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,021,094	1,040,675
Commercial and industrial | Originated | Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	93,228	108,608
Commercial and industrial | Originated | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	927,866	932,067
Commercial and industrial | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	44,291	50,976
Commercial and industrial | Acquired | Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0	0
Commercial and industrial | Acquired | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	44,291	50,976
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	2,321,158	2,200,727
Commercial real estate | Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	147,813	129,959
Commercial real estate | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,992,852	1,866,802
Commercial real estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	180,493	203,966
Commercial real estate | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	2,138,013	1,992,980
Commercial real estate | Originated | Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	147,582	129,712
Commercial real estate | Originated | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,811,348	1,660,782
Commercial real estate | Originated | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	179,083	202,486
Commercial real estate | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	183,145	207,747
Commercial real estate | Acquired | Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	231	247
Commercial real estate | Acquired | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	181,504	206,020
Commercial real estate | Acquired | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,410	1,480
Residential real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,338,406	1,302,941
Residential real estate | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	231,601	241,256
Residential real estate | Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,106,805	1,061,685
Residential real estate | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,295,233	1,251,852
Residential real estate | Originated | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	209,168	212,812
Residential real estate | Originated | Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	1,086,065	1,039,040
Residential real estate | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	43,173	51,089
Residential real estate | Acquired | Home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	22,433	28,444
Residential real estate | Acquired | Mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	20,740	22,645
Consumer and other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	67,302	63,123
Consumer and other | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	55,339	50,979
Consumer and other | Indirect
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	11,963	12,144
Consumer and other | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	66,443	62,358
Consumer and other | Originated | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	54,480	50,214
Consumer and other | Originated | Indirect
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	11,963	12,144
Consumer and other | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	859	765
Consumer and other | Acquired | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	859	765
Consumer and other | Acquired | Indirect
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	0	0
Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	14,055	14,467
Leases | Originated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	14,055	14,467
Leases | Acquired
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 0	$ 0