Commitments and Off-Balance Sheet Risk (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Summary of contractual amounts of financial instruments with off-balance sheet risk
Contractual amounts of financial instruments with off-balance sheet risk	$ 370,575,000	$ 334,768,000
Commercial unused lines of credit [Member]
Summary of contractual amounts of financial instruments with off-balance sheet risk
Contractual amounts of financial instruments with off-balance sheet risk	230,160,000	222,237,000
Unused lines of credit secured by 1 - 4 family residential properties [Member]
Summary of contractual amounts of financial instruments with off-balance sheet risk
Contractual amounts of financial instruments with off-balance sheet risk	23,892,000	24,250,000
Credit card unused lines of credit [Member]
Summary of contractual amounts of financial instruments with off-balance sheet risk
Contractual amounts of financial instruments with off-balance sheet risk	8,431,000	8,512,000
Other consumer unused lines of credit [Member]
Summary of contractual amounts of financial instruments with off-balance sheet risk
Contractual amounts of financial instruments with off-balance sheet risk	3,752,000	4,613,000
Commitments to extent credit [Member]
Summary of contractual amounts of financial instruments with off-balance sheet risk
Contractual amounts of financial instruments with off-balance sheet risk	94,000,000	64,565,000
Standby letters of credit [Member]
Summary of contractual amounts of financial instruments with off-balance sheet risk
Contractual amounts of financial instruments with off-balance sheet risk	$ 10,340,000	$ 10,591,000