Fair Value Measurements (Estimated Fair Values of Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Commitments to Extend Credit [Member]
Financial liabilities:
Off-balance sheet instruments	$ 397,300
Carrying Amount [Member]
Financial assets:
Cash and cash equivalents	48,246	55,073
Securities	796,268	810,094
Loans held for sale	14,179	9,359
Loans, net	1,466,597	1,415,048
Restricted investments in bank stock	15,170	16,802
Accrued interest receivable	7,223	7,378
Financial liabilities:
Deposits	2,085,915	2,071,574
Short-term borrowings	72,250	65,000
Long-term debt	49,200	49,200
Accrued interest payable	350	487
Carrying Amount [Member] | Standby Letters of Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0	0
Carrying Amount [Member] | Commitments to Extend Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0	0
Fair Value [Member]
Financial assets:
Cash and cash equivalents	48,246	55,073
Securities	800,149	813,316
Loans held for sale	14,465	9,474
Loans, net	1,482,551	1,436,323
Restricted investments in bank stock	15,170	16,802
Accrued interest receivable	7,223	7,378
Financial liabilities:
Deposits	2,087,889	2,074,139
Short-term borrowings	72,250	65,000
Long-term debt	40,342	39,773
Accrued interest payable	350	487
Fair Value [Member] | Standby Letters of Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0	0
Fair Value [Member] | Commitments to Extend Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0	0
Fair Value [Member] | Quoted Prices in Active Markets for Identical Assets, Level 1 [Member]
Financial assets:
Cash and cash equivalents	48,246
Securities	0
Loans held for sale	0
Loans, net	0
Restricted investments in bank stock	0
Accrued interest receivable	7,223
Financial liabilities:
Deposits	0
Short-term borrowings	72,250
Long-term debt	0
Accrued interest payable	350
Fair Value [Member] | Quoted Prices in Active Markets for Identical Assets, Level 1 [Member] | Standby Letters of Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0
Fair Value [Member] | Quoted Prices in Active Markets for Identical Assets, Level 1 [Member] | Commitments to Extend Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0
Fair Value [Member] | Significant Other Observable Inputs, Level 2 [Member]
Financial assets:
Cash and cash equivalents	0
Securities	800,149
Loans held for sale	0
Loans, net	0
Restricted investments in bank stock	0
Accrued interest receivable	0
Financial liabilities:
Deposits	0
Short-term borrowings	0
Long-term debt	0
Accrued interest payable	0
Fair Value [Member] | Significant Other Observable Inputs, Level 2 [Member] | Standby Letters of Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0
Fair Value [Member] | Significant Other Observable Inputs, Level 2 [Member] | Commitments to Extend Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0
Fair Value [Member] | Significant Unobservable Inputs, Level 3 [Member]
Financial assets:
Cash and cash equivalents	0
Securities	0
Loans held for sale	14,465
Loans, net	1,482,551
Restricted investments in bank stock	15,170
Accrued interest receivable	0
Financial liabilities:
Deposits	2,087,889
Short-term borrowings	0
Long-term debt	40,342
Accrued interest payable	0
Fair Value [Member] | Significant Unobservable Inputs, Level 3 [Member] | Standby Letters of Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0
Fair Value [Member] | Significant Unobservable Inputs, Level 3 [Member] | Commitments to Extend Credit [Member]
Financial liabilities:
Off-balance sheet instruments	$ 0