Securities Portfolio (Details) (USD $)	12 Months Ended
	Dec. 31, 2012 Securities	Dec. 31, 2011 Securities
Amortized cost and fair value of securities held-to-maturity [Abstract]
Amortized Cost	$ 570,000	$ 1,515,000
Gross Unrealized Gains	4,000	11,000
Gross Unrealized Losses	0	0
Fair Value	574,000	1,526,000
Amortized cost and fair value of securities available-for-sale [Abstract]
Amortized Cost	326,436,000	234,287,000
Gross Unrealized Gains	3,992,000	2,368,000
Gross Unrealized Losses	(972,000)	(56,000)
Fair Value	329,456,000	236,599,000
Securities pledged as collateral	89,500,000	85,400,000
Securities Available-for-Sale, Gross Unrealized Losses [Abstract]
Less Than Twelve Months	972,000	56,000
More Than Twelve Months	0	0
Total	972,000	56,000
Securities Available-for-Sale, Fair Value [Abstract]
Less than Twelve Months	119,404,000	31,070,000
More Than Twelve Months	0	0
Total	119,404,000	31,070,000
Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Cause	caused by increases in market interest rates.
Number of securities	36,000	5,000
Number of unrealized losses positions	36,000	5,000
Available-for-Sale, Amortized Cost [Abstract]
Due in one year or less	392,000
Due after one year through five years	39,400,000
Due after five years through ten years	26,749,000
Due after ten years	259,354,000
Total debt securities	325,895,000
Other securities without stated maturities	541,000
Total securities	326,436,000
Available-for-Sale, Fair Value [Abstract]
Due in one year or less	393,000
Due after one year through five years	40,794,000
Due after five years through ten years	27,018,000
Due after ten years	260,710,000
Total debt securities	328,915,000
Other securities without stated maturities	541,000
Fair Value	329,456,000
Held-to-Maturity, Amortized Cost [Abstract]
Due in one year or less	270,000
Due after one year through five years	300,000
Due after five years through ten years	0
Due after ten years	0
Total debt securities	570,000
Other securities without stated maturities	0
Total securities	570,000
Held-to-Maturity, Fair Value [Abstract]
Due in one year or less	271,000
Due after one year through five years	303,000
Due after five years through ten years	0
Due after ten years	0
Total debt securities	574,000
Other securities without stated maturities	0
Total securities	574,000
Information about securities sold [Abstract]
Proceeds from sales	198,217,000	94,716,000
Gross realized gains	2,313,000	787,000
Gross realized losses	0	0
US Treasury securities [Member]
Amortized cost and fair value of securities available-for-sale [Abstract]
Amortized Cost		250,000
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Fair Value		250,000
Obligations of US Government agencies [Member]
Amortized cost and fair value of securities available-for-sale [Abstract]
Amortized Cost	35,787,000	117,848,000
Gross Unrealized Gains	1,314,000	1,706,000
Gross Unrealized Losses	(13,000)	0
Fair Value	37,088,000	119,554,000
Securities Available-for-Sale, Gross Unrealized Losses [Abstract]
Less Than Twelve Months	13,000
More Than Twelve Months	0
Total	13,000
Securities Available-for-Sale, Fair Value [Abstract]
Less than Twelve Months	5,103,000
More Than Twelve Months	0
Total	5,103,000
Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Number of securities	1,000
Number of unrealized losses positions	1,000
Obligations of states and political subdivisions [Member]
Amortized cost and fair value of securities available-for-sale [Abstract]
Amortized Cost	43,276,000	11,999,000
Gross Unrealized Gains	712,000	266,000
Gross Unrealized Losses	(214,000)	(4,000)
Fair Value	43,774,000	12,261,000
Securities Available-for-Sale, Gross Unrealized Losses [Abstract]
Less Than Twelve Months	214,000	4,000
More Than Twelve Months	0	0
Total	214,000	4,000
Securities Available-for-Sale, Fair Value [Abstract]
Less than Twelve Months	9,535,000	1,706,000
More Than Twelve Months	0	0
Total	9,535,000	1,706,000
Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Number of securities	24,000	2,000
Number of unrealized losses positions	24,000	2,000
Mortgage-backed securities [Member]
Amortized cost and fair value of securities available-for-sale [Abstract]
Amortized Cost	246,132,000	102,884,000
Gross Unrealized Gains	1,966,000	396,000
Gross Unrealized Losses	(743,000)	(52,000)
Fair Value	247,355,000	103,228,000
Securities Available-for-Sale, Gross Unrealized Losses [Abstract]
Less Than Twelve Months	743,000	52,000
More Than Twelve Months	0	0
Total	743,000	52,000
Securities Available-for-Sale, Fair Value [Abstract]
Less than Twelve Months	104,066,000	29,364,000
More Than Twelve Months	0	0
Total	104,066,000	29,364,000
Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Number of securities	9,000	3,000
Number of unrealized losses positions	9,000	3,000
Money market investments [Member]
Amortized cost and fair value of securities available-for-sale [Abstract]
Amortized Cost	541,000	1,306,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	541,000	1,306,000
Corporate bond and other securities [Member]
Securities Available-for-Sale, Gross Unrealized Losses [Abstract]
Less Than Twelve Months	2,000
More Than Twelve Months	0
Total	2,000
Securities Available-for-Sale, Fair Value [Abstract]
Less than Twelve Months	700,000
More Than Twelve Months	0
Total	700,000
Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Number of securities	2,000
Number of unrealized losses positions	2,000
Corporate Bonds [Member]
Amortized cost and fair value of securities available-for-sale [Abstract]
Amortized Cost	700,000
Gross Unrealized Gains	0
Gross Unrealized Losses	(2,000)
Fair Value	698,000
Obligations of US Government agencies [Member]
Amortized cost and fair value of securities held-to-maturity [Abstract]
Amortized Cost	570,000	1,370,000
Gross Unrealized Gains	4,000	8,000
Gross Unrealized Losses	0	0
Fair Value	574,000	1,378,000
Obligations of states and political subdivisions [Member]
Amortized cost and fair value of securities held-to-maturity [Abstract]
Amortized Cost		145,000
Gross Unrealized Gains		3,000
Gross Unrealized Losses		0
Fair Value		$ 148,000