Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended		12 Months Ended
	Sep. 30, 2013		Dec. 31, 2012
Fair Value Assets And Liabilities Measured On Nonrecurring Basis [Abstract]
Non-covered other real estate owned	$ 4,747		$ 3,023
Covered other real estate owned	4,109		13,460
Non-Covered Impaired Loans with Appraisal Adjustments [Abstract]
Non-covered impaired loans, appraisal frequency	12 months
Losses For The Period On Nonrecurring Valuated Assets [Abstract]
Total losses for the period, non-covered impaired loans	(4,407)	[1]	(8,485)	[1]
Total losses for the period, non covered other real estate owned	(542)	[2]	(844)	[2]
Total losses for the period, covered other real estate owned	(1,386)	[2]	(3,704)	[2]
Total	(6,335)		(13,033)
Fair Value Assets And Liabilities Measured On Nonrecurring Basis Other Disclosures [Abstract]
Percentage deducted of the appraised value to cover selling costs (in hundredths)	10.00%
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
U.S. government agencies	85,915		88,586
Residential pass-through securities	168,819		168,423
Taxable state and political subdivisions	2,510		5,312
Tax exempt state and political subdivisions	72,399		58,985
Corporate obligations	10,748		10,435
Agency-issued collateralized mortgage obligations	35,738		14,046
Asset-backed securities	22,234		25,188
Investments in mutual funds and other equities	1,913		1,993
Total	400,276		372,968
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
U.S. government agencies	0		0
Residential pass-through securities	0		0
Taxable state and political subdivisions	0		0
Tax exempt state and political subdivisions	0		0
Corporate obligations	5,798		2,985
Agency-issued collateralized mortgage obligations	0		0
Asset-backed securities	0		0
Investments in mutual funds and other equities	1,913		1,993
Total	7,711		4,978
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
U.S. government agencies	85,915		88,586
Residential pass-through securities	168,819		168,423
Taxable state and political subdivisions	2,510		5,312
Tax exempt state and political subdivisions	72,399		58,985
Corporate obligations	4,950		7,450
Agency-issued collateralized mortgage obligations	35,738		14,046
Asset-backed securities	22,234		25,188
Investments in mutual funds and other equities	0		0
Total	392,565		367,990
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
U.S. government agencies	0		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		0
Asset-backed securities	0		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	30,625	[1]	38,299	[1]
Non-covered other real estate owned	4,747	[2]	3,023	[2]
Covered other real estate owned	4,109	[2]	13,460	[2]
Total fair value measurements, nonrecurring	39,481		54,782
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	30,625	[1]	38,299	[1]
Non-covered other real estate owned	4,747	[2]	3,023	[2]
Covered other real estate owned	4,109	[2]	13,460	[2]
Total fair value measurements, nonrecurring	39,481		54,782
Non-Covered Impaired Loans with Appraisal Adjustments [Abstract]
Number of impaired loans with appraisal adjustments	1
Impaired loans with adjustments to appraisals, amount	$ 105
Appraisal adjustment to impaired loan, percentage change	30.00%

[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.