Fair Value of Assets and Liabilities, Part II (Details) - USD ($)		3 Months Ended	12 Months Ended
		Mar. 31, 2017	Dec. 31, 2016
Foreclosed Assets Held for Sale [Abstract]
Other real estate owned		$ 2,433,000	$ 1,982,000
Assets Measured On Recurring And Nonrecurring Basis Valuation Techniques [Abstract]
Assets, Fair Value Disclosure, Recurring		1,638,000	1,652,000
Financial Assets [Abstract]
Available-for-sale securities		694,321,000	619,848,000
Held-to-maturity Securities		74,256,000	74,231,000
Held-to-maturity Securities, Fair Value		73,754,000	73,096,000
Financial Liabilities [Abstract]
Other borrowings		13,125,000	18,063,000
Carrying Amount [Member]
Financial Assets [Abstract]
Cash and due from banks		112,759,000	137,002,000
Federal funds sold		491,000	38,900,000
Certificates of deposit investments		1,685,000	14,643,000
Available-for-sale securities		694,321,000	619,848,000
Held-to-maturity Securities		74,256,000	74,231,000
Loans held for sale		1,578,000	1,175,000
Loans net of allowance for loan losses		1,776,238,000	1,808,064,000
Interest receivable		9,786,000	10,553,000
Federal Reserve Bank stock		4,128,000	3,949,000
Federal Home Loan Bank stock		2,554,000	4,389,000
Financial Liabilities [Abstract]
Deposits		2,329,529,000	2,329,887,000
Securities sold under agreements to repurchase		143,864,000	185,763,000
Interest payable		484,000	535,000
Federal Home Loan Bank borrowings		40,080,000	40,094,000
Other Liabilities, Fair Value Disclosure			18,063,000
Other borrowings		13,125,000
Junior subordinated debentures		23,938,000	23,917,000
Fair Value [Member]
Financial Assets [Abstract]
Cash and due from banks		112,759,000	137,002,000
Federal funds sold		491,000	38,900,000
Certificates of deposit investments		1,711,000	14,651,000
Available-for-sale securities		694,321,000	619,848,000
Held-to-maturity Securities, Fair Value		73,754,000	73,096,000
Loans held for sale		1,578,000	1,175,000
Loans net of allowance for loan losses		1,772,522,000	1,795,764,000
Interest receivable		9,786,000	10,553,000
Federal Reserve Bank stock		4,128,000	3,949,000
Federal Home Loan Bank stock		2,554,000	4,389,000
Financial Liabilities [Abstract]
Deposits		2,334,652,000	2,331,725,000
Securities sold under agreements to repurchase		143,850,000	185,766,000
Interest payable		484,000	535,000
Federal Home Loan Bank borrowings		40,346,000	40,318,000
Other Liabilities, Fair Value Disclosure			18,063,000
Other borrowings		13,125,000
Junior subordinated debentures		17,250,000	17,068,000
Fair Value, Measurements, Nonrecurring [Member] | Carrying Amount [Member]
Foreclosed Assets Held for Sale [Abstract]
Other real estate owned		2,433,000
Fair Value, Measurements, Nonrecurring [Member] | Fair Value [Member]
Foreclosed Assets Held for Sale [Abstract]
Other real estate owned		0
Quoted Prices in Active Markets for Identical Assets (Level 1)
Financial Assets [Abstract]
Cash and due from banks		112,759,000	137,002,000
Federal funds sold		491,000	38,900,000
Certificates of deposit investments		0	0
Available-for-sale securities		133,000	144,000
Held-to-maturity Securities, Fair Value		0	0
Loans held for sale		0	0
Loans net of allowance for loan losses		0	0
Interest receivable		0	0
Federal Reserve Bank stock		0	0
Federal Home Loan Bank stock		0	0
Financial Liabilities [Abstract]
Deposits		0	0
Securities sold under agreements to repurchase		0	0
Interest payable		0	0
Federal Home Loan Bank borrowings		0	0
Other borrowings		0	0
Junior subordinated debentures		0	0
Significant Other Observable Inputs (Level 2)
Financial Assets [Abstract]
Cash and due from banks		0	0
Federal funds sold		0	0
Certificates of deposit investments		1,711,000	14,651,000
Available-for-sale securities		692,550,000	618,052,000
Held-to-maturity Securities, Fair Value		73,754,000	73,096,000
Loans held for sale		1,578,000	1,175,000
Loans net of allowance for loan losses		0	0
Interest receivable		9,786,000	10,553,000
Federal Reserve Bank stock		4,128,000	3,949,000
Federal Home Loan Bank stock		2,554,000	4,389,000
Financial Liabilities [Abstract]
Deposits		1,989,612,000	1,976,806,000
Securities sold under agreements to repurchase		143,850,000	185,766,000
Interest payable		484,000	535,000
Federal Home Loan Bank borrowings		40,346,000	40,318,000
Other borrowings		13,125,000	18,063,000
Junior subordinated debentures		17,250,000	17,068,000
Significant Unobservable Inputs (Level 3)
Financial Assets [Abstract]
Cash and due from banks		0	0
Federal funds sold		0	0
Certificates of deposit investments		0	0
Available-for-sale securities		1,638,000	1,652,000
Held-to-maturity Securities, Fair Value		0	0
Loans held for sale		0	0
Loans net of allowance for loan losses		1,772,522,000	1,795,764,000
Interest receivable		0	0
Federal Reserve Bank stock		0	0
Federal Home Loan Bank stock		0	0
Financial Liabilities [Abstract]
Deposits		345,040,000	354,919,000
Securities sold under agreements to repurchase		0	0
Interest payable		0	0
Federal Home Loan Bank borrowings		0	0
Other borrowings		0	0
Junior subordinated debentures		$ 0	$ 0
Trust preferred securities | Significant Unobservable Inputs (Level 3) | Discounted Cash Flow [Member]
Assets Measured On Recurring And Nonrecurring Basis Valuation Techniques [Abstract]
Discount rate (in hundredths)		13.40%	13.60%
Constant prepayment rate (in hundredths)	[1]	1.30%	1.30%
Cumulative projected prepayments (in hundredths)		22.10%	22.40%
Probability of default (in hundredths)		0.50%	0.50%
Loss severity (in hundredths)		97.60%	97.60%
Projected cures given deferral (in hundredths)		0.00%	0.00%
Impaired loans (collateral dependent) | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets, Fair Value Disclosure, Nonrecurring		$ 8,418,000	$ 6,938,000
Impaired loans (collateral dependent) | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets, Fair Value Disclosure, Nonrecurring		0	0
Impaired loans (collateral dependent) | Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets, Fair Value Disclosure, Nonrecurring		$ 0	$ 0
Impaired loans (collateral dependent) | Significant Unobservable Inputs (Level 3) | Minimum [Member] | Third Party Valuations [Member]
Assets Measured On Recurring And Nonrecurring Basis Valuation Techniques [Abstract]
Discount to reflect realizable value (in hundredths)		0.00%	0.00%
Impaired loans (collateral dependent) | Significant Unobservable Inputs (Level 3) | Maximum [Member] | Third Party Valuations [Member]
Assets Measured On Recurring And Nonrecurring Basis Valuation Techniques [Abstract]
Discount to reflect realizable value (in hundredths)		40.00%	40.00%
Impaired loans (collateral dependent) | Significant Unobservable Inputs (Level 3) | Weighted Average [Member] | Third Party Valuations [Member]
Assets Measured On Recurring And Nonrecurring Basis Valuation Techniques [Abstract]
Discount to reflect realizable value (in hundredths)		20.00%	20.00%
Impaired loans (collateral dependent) | Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets, Fair Value Disclosure, Nonrecurring		$ 8,418,000	$ 6,938,000
Assets Held-for-sale [Member] | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets, Fair Value Disclosure, Nonrecurring		0	173,000
Assets Held-for-sale [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets, Fair Value Disclosure, Nonrecurring		0	0
Assets Held-for-sale [Member] | Significant Other Observable Inputs (Level 2) | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets, Fair Value Disclosure, Nonrecurring		0	$ 0
Assets Held-for-sale [Member] | Significant Unobservable Inputs (Level 3) | Minimum [Member] | Third Party Valuations [Member]
Assets Measured On Recurring And Nonrecurring Basis Valuation Techniques [Abstract]
Discount to reflect realizable value less estimated selling costs (in hundredths)			0.00%
Assets Held-for-sale [Member] | Significant Unobservable Inputs (Level 3) | Maximum [Member] | Third Party Valuations [Member]
Assets Measured On Recurring And Nonrecurring Basis Valuation Techniques [Abstract]
Discount to reflect realizable value less estimated selling costs (in hundredths)			40.00%
Assets Held-for-sale [Member] | Significant Unobservable Inputs (Level 3) | Weighted Average [Member] | Third Party Valuations [Member]
Assets Measured On Recurring And Nonrecurring Basis Valuation Techniques [Abstract]
Discount to reflect realizable value (in hundredths)			35.00%
Assets Held-for-sale [Member] | Significant Unobservable Inputs (Level 3) | Fair Value, Measurements, Nonrecurring [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Assets, Fair Value Disclosure, Nonrecurring		$ 0	$ 173,000

[1] Every five years