Fair Value Measurements (Estimated Fair Values of Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Commitments to Extend Credit [Member]
Financial liabilities:
Off-balance sheet instruments	$ 451,200
Carrying Amount [Member]
Financial assets:
Cash and cash equivalents	138,468	55,073
Securities	792,909	810,094
Loans held for sale	8,851	9,359
Loans, net	1,479,394	1,415,048
Restricted investments in bank stock	13,725	16,802
Accrued interest receivable	6,934	7,378
Financial liabilities:
Deposits	2,243,932	2,071,574
Short-term borrowings		65,000
Long-term debt	49,200	49,200
Accrued interest payable	273	487
Carrying Amount [Member] | Commitments to Extend Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0	0
Carrying Amount [Member] | Standby Letters of Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0	0
Fair Value [Member]
Financial assets:
Cash and cash equivalents	138,468	55,073
Securities	797,360	813,316
Loans held for sale	9,024	9,474
Loans, net	1,494,063	1,436,323
Restricted investments in bank stock	13,725	16,802
Accrued interest receivable	6,934	7,378
Financial liabilities:
Deposits	2,245,730	2,074,139
Short-term borrowings		65,000
Long-term debt	42,675	39,773
Accrued interest payable	273	487
Fair Value [Member] | Commitments to Extend Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0	0
Fair Value [Member] | Standby Letters of 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	138,468
Securities	0
Loans held for sale	0
Loans, net	0
Restricted investments in bank stock	0
Accrued interest receivable	6,934
Financial liabilities:
Deposits	0
Long-term debt	0
Accrued interest payable	273
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] | 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] | Significant Other Observable Inputs, Level 2 [Member]
Financial assets:
Cash and cash equivalents	0
Securities	797,360
Loans held for sale	0
Loans, net	0
Restricted investments in bank stock	0
Accrued interest receivable	0
Financial liabilities:
Deposits	0
Long-term debt	0
Accrued interest payable	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 Other Observable Inputs, Level 2 [Member] | Standby Letters of 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	9,024
Loans, net	1,494,063
Restricted investments in bank stock	13,725
Accrued interest receivable	0
Financial liabilities:
Deposits	2,245,730
Long-term debt	42,675
Accrued interest payable	0
Fair Value [Member] | Significant Unobservable Inputs, Level 3 [Member] | Commitments to Extend Credit [Member]
Financial liabilities:
Off-balance sheet instruments	0
Fair Value [Member] | Significant Unobservable Inputs, Level 3 [Member] | Standby Letters of Credit [Member]
Financial liabilities:
Off-balance sheet instruments	$ 0