Fair Value Measurements (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013 Property MutualFunds		Dec. 31, 2012 Property
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of mutual funds that invest in debt securities or loans that qualify for credit under the Community Reinvestment Act	2
Nonrecurring fair value measurements [Abstract]
Number of impaired other real estate owned properties	2		8
Other real estate owned impaired carrying value	$ 173,000		$ 1,809,000
Fair value of other real estate owned properties	156,000		1,525,000
Impaired charges related to other real estate owned properties included in non-interest expense for the period	17,000		284,000
Number of other real estate owned properties sold	4
Other real estate owned properties sold during period carrying value	612,000
Proceeds from sale of other real estate owned properties	857,000
Gain on sales of other real estate properties	245,000
Loss on sale of property			8,000
Carrying value of repossessed asset	6,000		23,000
Proceeds from sale of repossessed assets	8,000		20,000
Realized gain (loss) from sale of repossessed assets	2,000		(3,000)
Assets [Abstract]
Loans, net	550,404,000		448,784,000
Investment securities, non-taxable, held-to-maturity	22,831,000		15,424,000
Federal Reserve Bank stock	1,106,000		949,000
Federal Home Loan Bank stock	2,854,000		2,091,000
Liabilities [Abstract]
Deposits	825,318,000		675,964,000
Long-term debt	14,066,000		14,724,000
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets [Abstract]
Loans, net	0		0
Investment securities, non-taxable, held-to-maturity	0		0
Federal Reserve Bank stock	1,106,000		949,000
Federal Home Loan Bank stock	2,854,000		2,091,000
Liabilities [Abstract]
Deposits	0		0
Long-term debt	0		0
Significant Other Observable Inputs (Level 2) [Member]
Assets [Abstract]
Loans, net	550,404,000		448,784,000
Investment securities, non-taxable, held-to-maturity	0		0
Federal Reserve Bank stock	0		0
Federal Home Loan Bank stock	0		0
Liabilities [Abstract]
Deposits	825,318,000		675,964,000
Long-term debt	14,066,000		14,724,000
Significant Unobservable Inputs (Level 3) [Member]
Assets [Abstract]
Loans, net	0		0
Investment securities, non-taxable, held-to-maturity	22,831,000		15,424,000
Federal Reserve Bank stock	0		0
Federal Home Loan Bank stock	0		0
Liabilities [Abstract]
Deposits	0		0
Long-term debt	0		0
Recurring [Member]
Investment securities available-for-sale [Abstract]
U.S. Treasury notes	19,693,000		18,686,000
U.S. Agency notes	101,499,000		90,606,000
U.S. Agency mortgage-backed securities	54,156,000		52,541,000
Corporate securities			3,067,000
Certificates of deposit with other banks	1,509,000
Municipal securities [Abstract]
Non-taxable	78,744,000		73,882,000
Taxable	17,592,000		15,841,000
Mutual funds	2,223,000		2,168,000
Trust preferred securities	148,000		245,000
Equity securities	1,995,000		1,470,000
Total recurring fair value measurements	277,559,000		258,506,000
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Investment securities available-for-sale [Abstract]
U.S. Treasury notes	19,693,000		18,686,000
U.S. Agency notes	0		0
U.S. Agency mortgage-backed securities	0		0
Corporate securities			3,067,000
Certificates of deposit with other banks	0
Municipal securities [Abstract]
Non-taxable	0		0
Taxable	0		0
Mutual funds	1,223,000		1,168,000
Trust preferred securities	148,000		245,000
Equity securities	1,995,000		1,470,000
Total recurring fair value measurements	23,059,000		24,636,000
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Investment securities available-for-sale [Abstract]
U.S. Treasury notes	0		0
U.S. Agency notes	101,499,000		90,606,000
U.S. Agency mortgage-backed securities	54,156,000		52,541,000
Corporate securities			0
Certificates of deposit with other banks	1,509,000
Municipal securities [Abstract]
Non-taxable	78,744,000		73,882,000
Taxable	17,592,000		15,841,000
Mutual funds	1,000,000		1,000,000
Trust preferred securities	0		0
Equity securities	0		0
Total recurring fair value measurements	254,500,000		233,870,000
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Investment securities available-for-sale [Abstract]
U.S. Treasury notes	0		0
U.S. Agency notes	0		0
U.S. Agency mortgage-backed securities	0		0
Corporate securities			0
Certificates of deposit with other banks	0
Municipal securities [Abstract]
Non-taxable	0		0
Taxable	0		0
Mutual funds	0		0
Trust preferred securities	0		0
Equity securities	0		0
Total recurring fair value measurements	0		0
Recurring [Member] | Total Gains (Losses) [Member]
Investment securities available-for-sale [Abstract]
U.S. Treasury notes	0		0
U.S. Agency notes	0		0
U.S. Agency mortgage-backed securities	0		0
Corporate securities			0
Municipal securities [Abstract]
Non-taxable	0		0
Taxable	0		0
Mutual funds	0		0
Trust preferred securities	0		0
Equity securities	0		0
Total recurring fair value measurements	0		0
Nonrecurring [Member]
Nonrecurring fair value measurements [Abstract]
Impaired loans	4,589,000		4,276,000
Other real estate owned and repossessed assets	1,687,000	[1]	2,189,000	[2]
Total nonrecurring fair value measurements	6,276,000		6,465,000
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Nonrecurring fair value measurements [Abstract]
Impaired loans	0		0
Other real estate owned and repossessed assets	0	[1]	0	[2]
Total nonrecurring fair value measurements	0		0
Nonrecurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Nonrecurring fair value measurements [Abstract]
Impaired loans	707,000		161,000
Other real estate owned and repossessed assets	1,687,000	[1]	2,189,000	[2]
Total nonrecurring fair value measurements	2,394,000		2,350,000
Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Nonrecurring fair value measurements [Abstract]
Impaired loans	3,882,000		4,115,000
Other real estate owned and repossessed assets	0	[1]	0	[2]
Total nonrecurring fair value measurements	3,882,000		4,115,000
Nonrecurring [Member] | Total Gains (Losses) [Member]
Nonrecurring fair value measurements [Abstract]
Impaired loans	0		0
Other real estate owned and repossessed assets	230,000	[1]	(295,000)	[2]
Total nonrecurring fair value measurements	$ 230,000		$ (295,000)

[1] Two other real estate owned properties with a total carrying amount of $173,000 were written down to their combined fair value of $156,000, resulting in an impairment charge of $17,000. Four other real estate owned properties with a total carrying amount of $612,000 were sold for a combined total of $857,000, resulting in a net gain of $245,000. A repossessed asset with a carrying value of $6,000 was sold for $8,000, resulting in a net gain of $2,000. The write-downs, losses, and gains were included in other non-interest expense for the period.

[2] Eight other real estate owned properties with a total carrying amount of $1,809,000 were written down to their combined fair value of $1,525,000, resulting in an impairment charge of $284,000. Another property was sold at a loss of $8,000. Repossessed assets with a carrying value of $23,000 were sold for a combined total of $20,000, resulting in a net loss of $3,000. The write-downs and losses were included in other non-interest expense for the period.