Fair Value Measurements (Details) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Fair value assets and liabilities measured on nonrecurring basis [Abstract]
Non-covered other real estate owned	$ 3,023,000		$ 1,976,000
Covered other real estate owned	13,460,000		26,622,000
Losses For The Period On Nonrecurring Valuated Assets [Abstract]
Total losses for the period, non-covered impaired loans	(8,485,000)	[1]	(8,182,000)	[1]
Total losses for the period, non-covered other real estate owned	(844,000)	[2]	(272,000)	[2]
Total losses for the period, covered other real estate owned	(3,704,000)	[2]	(6,672,000)	[2]
Total	(13,033,000)		(15,126,000)
Fair Value Assets And Liabilities Measured On Nonrecurring Basis Other Disclosures [Abstract]
Impaired loans with adjustments to appraisals	8,700,000
Percentage deducted of the appraised value to cover selling costs (in hundredths)	10.00%
Minimum [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis Other Disclosures [Abstract]
Impaired loans, adjustments to appraisals based on unobservable inputs	10.00%
Maximum [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis Other Disclosures [Abstract]
Impaired loans, adjustments to appraisals based on unobservable inputs	57.00%
Weighted Average [Member]
Fair Value Assets And Liabilities Measured On Nonrecurring Basis Other Disclosures [Abstract]
Impaired loans, adjustments to appraisals based on unobservable inputs	27.00%
Fair Value, Measurements, Recurring [Member]
Fair value assets and liabilities measured on recurring basis [Abstract]
U.S. government agencies	88,586,000		76,574,000
U.S. Treasuries			42,597,000
Residential pass-through securities	168,423,000		117,398,000
Taxable state and political subdivisions	5,312,000		9,758,000
Tax exempt state and political subdivisions	58,985,000		37,335,000
Corporate obligations	10,435,000		10,287,000
Agency-issued collateralized mortgage obligations	14,046,000
Asset-backed securities	25,188,000
Investments in mutual funds and other equities	1,993,000		2,006,000
Total	372,968,000		295,955,000
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair value assets and liabilities measured on recurring basis [Abstract]
U.S. government agencies	0		0
U.S. Treasuries			0
Residential pass-through securities	0		0
Taxable state and political subdivisions	0		0
Tax exempt state and political subdivisions	0		0
Corporate obligations	0		0
Agency-issued collateralized mortgage obligations	0
Asset-backed securities	0
Investments in mutual funds and other equities	0		0
Total	0		0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair value assets and liabilities measured on recurring basis [Abstract]
U.S. government agencies	88,586,000		76,574,000
U.S. Treasuries			42,597,000
Residential pass-through securities	168,423,000		117,398,000
Taxable state and political subdivisions	5,312,000		9,758,000
Tax exempt state and political subdivisions	58,985,000		37,335,000
Corporate obligations	10,435,000		10,287,000
Agency-issued collateralized mortgage obligations	14,046,000
Asset-backed securities	25,188,000
Investments in mutual funds and other equities	1,993,000		2,006,000
Total	372,968,000		295,955,000
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair value assets and liabilities measured on recurring basis [Abstract]
U.S. government agencies	0		0
U.S. Treasuries			0
Residential pass-through securities	0		0
Taxable state and political subdivisions	0		0
Tax exempt state and political subdivisions	0		0
Corporate obligations	0		0
Agency-issued collateralized mortgage obligations	0
Asset-backed securities	0
Investments in mutual funds and other equities	0		0
Total	0		0
Fair Value, Measurements, Nonrecurring [Member]
Fair value assets and liabilities measured on nonrecurring basis [Abstract]
Non-covered impaired loans	38,299,000	[1]	44,845,000	[1]
Non-covered other real estate owned	3,023,000	[2]	1,976,000	[2]
Covered other real estate owned	13,460,000	[2]	26,622,000	[2]
Total fair value measurements, nonrecurring	54,782,000		73,443,000
Fair Value, Measurements, Nonrecurring [Member] | Level 1 [Member]
Fair value assets and liabilities measured on nonrecurring basis [Abstract]
Non-covered impaired loans	0	[1]	0	[1]
Non-covered other real estate owned	0	[2]	0	[2]
Covered other real estate owned	0	[2]	0	[2]
Total fair value measurements, nonrecurring	0		0
Fair Value, Measurements, Nonrecurring [Member] | Level 2 [Member]
Fair value assets and liabilities measured on nonrecurring basis [Abstract]
Non-covered impaired loans	0	[1]	0	[1]
Non-covered other real estate owned	0	[2]	0	[2]
Covered other real estate owned	0	[2]	0	[2]
Total fair value measurements, nonrecurring	0		0
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member]
Fair value assets and liabilities measured on nonrecurring basis [Abstract]
Non-covered impaired loans	38,299,000	[1]	44,845,000	[1]
Non-covered other real estate owned	3,023,000	[2]	1,976,000	[2]
Covered other real estate owned	13,460,000	[2]	26,622,000	[2]
Total fair value measurements, nonrecurring	$ 54,782,000		$ 73,443,000

[1] Represents carrying value and related specific valuation allowances, which are included in the allowance for loan losses.

[2] Represents the fair value and related losses of foreclosed real estate and other collateral owned that were measured at fair value subsequent to their initial classification as non-covered other real estate owned and covered other real estate owned.