Allowance for Loan and Lease Losses - Credit Quality Indicators by Class of Commercial Real Estate (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Originated Loans and Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 3,195,492	$ 3,033,655
Originated Loans and Leases | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	3,123,455	2,968,737
Originated Loans and Leases | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	28,074	44,334
Originated Loans and Leases | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	43,963	20,584
Originated Loans and Leases | Commercial and industrial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	926,429	932,067
Originated Loans and Leases | Commercial and industrial | Other | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	910,476	919,214
Originated Loans and Leases | Commercial and industrial | Other | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	8,675	6,680
Originated Loans and Leases | Commercial and industrial | Other | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	7,278	6,173
Originated Loans and Leases | Commercial and industrial | Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	107,494	108,608
Originated Loans and Leases | Commercial and industrial | Agriculture | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	93,939	100,470
Originated Loans and Leases | Commercial and industrial | Agriculture | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	4,951	8,068
Originated Loans and Leases | Commercial and industrial | Agriculture | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	8,604	70
Originated Loans and Leases | Commercial real estate | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	1,827,279	1,660,782
Originated Loans and Leases | Commercial real estate | Other | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	1,797,599	1,627,713
Originated Loans and Leases | Commercial real estate | Other | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	9,484	19,068
Originated Loans and Leases | Commercial real estate | Other | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	20,196	14,001
Originated Loans and Leases | Commercial real estate | Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	170,005	129,712
Originated Loans and Leases | Commercial real estate | Agriculture | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	157,156	119,392
Originated Loans and Leases | Commercial real estate | Agriculture | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	4,964	9,980
Originated Loans and Leases | Commercial real estate | Agriculture | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	7,885	340
Originated Loans and Leases | Commercial real estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	164,285	202,486
Originated Loans and Leases | Commercial real estate | Construction | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	164,285	201,948
Originated Loans and Leases | Commercial real estate | Construction | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	0	538
Originated Loans and Leases | Commercial real estate | Construction | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	0	0
Acquired Loans and Leases
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	222,804	258,723
Acquired Loans and Leases | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	219,438	251,103
Acquired Loans and Leases | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	452	2,265
Acquired Loans and Leases | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	2,914	5,355
Acquired Loans and Leases | Commercial and industrial | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	43,712	50,976
Acquired Loans and Leases | Commercial and industrial | Other | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	43,447	50,554
Acquired Loans and Leases | Commercial and industrial | Other | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	0	0
Acquired Loans and Leases | Commercial and industrial | Other | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	265	422
Acquired Loans and Leases | Commercial and industrial | Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	0	0
Acquired Loans and Leases | Commercial and industrial | Agriculture | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	0	0
Acquired Loans and Leases | Commercial and industrial | Agriculture | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	0	0
Acquired Loans and Leases | Commercial and industrial | Agriculture | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	0	0
Acquired Loans and Leases | Commercial real estate | Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	177,484	206,020
Acquired Loans and Leases | Commercial real estate | Other | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	174,383	198,822
Acquired Loans and Leases | Commercial real estate | Other | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	452	2,265
Acquired Loans and Leases | Commercial real estate | Other | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	2,649	4,933
Acquired Loans and Leases | Commercial real estate | Agriculture
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	224	247
Acquired Loans and Leases | Commercial real estate | Agriculture | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	224	247
Acquired Loans and Leases | Commercial real estate | Agriculture | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	0	0
Acquired Loans and Leases | Commercial real estate | Agriculture | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	0	0
Acquired Loans and Leases | Commercial real estate | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	1,384	1,480
Acquired Loans and Leases | Commercial real estate | Construction | Pass
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	1,384	1,480
Acquired Loans and Leases | Commercial real estate | Construction | Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	0	0
Acquired Loans and Leases | Commercial real estate | Construction | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 0	$ 0