Investment Securities - Unrealized Loss Position (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Amount of securities in an unrealized loss position
Less than Twelve Months Fair Value	$ 75,079	$ 62,697
Less than Twelve Months Unrealized Losses	(317)	(300)
Twelve Months or Longer Fair value		480
Twelve Months or Longer Unrealized Losses		(12)
Total Fair Value	75,079	63,177
Total gross unrealized loss	(317)	(312)
U.S. treasuries [Member]
Amount of securities in an unrealized loss position
Less than Twelve Months Fair Value	4,936	4,938
Less than Twelve Months Unrealized Losses	(26)	(22)
Twelve Months or Longer Fair value
Twelve Months or Longer Unrealized Losses
Total Fair Value	4,936	4,938
Total gross unrealized loss	(26)	(22)
U.S. government corporations and agencies [Member]
Amount of securities in an unrealized loss position
Less than Twelve Months Fair Value	35,879	36,793
Less than Twelve Months Unrealized Losses	(57)	(75)
Twelve Months or Longer Fair value
Twelve Months or Longer Unrealized Losses
Total Fair Value	35,879	36,793
Total gross unrealized loss	(57)	(75)
State and political subdivisions [Member]
Amount of securities in an unrealized loss position
Less than Twelve Months Fair Value	6,634	4,574
Less than Twelve Months Unrealized Losses	(38)	(14)
Twelve Months or Longer Fair value		480
Twelve Months or Longer Unrealized Losses		(12)
Total Fair Value	6,634	5,054
Total gross unrealized loss	(38)	(26)
Collateralized mortgage obligations [Member]
Amount of securities in an unrealized loss position
Less than Twelve Months Fair Value	7,273	5,006
Less than Twelve Months Unrealized Losses	(11)	(5)
Twelve Months or Longer Fair value
Twelve Months or Longer Unrealized Losses
Total Fair Value	7,273	5,006
Total gross unrealized loss	(11)	(5)
Corporate bonds [Member]
Amount of securities in an unrealized loss position
Less than Twelve Months Fair Value	20,357	10,410
Less than Twelve Months Unrealized Losses	(185)	(51)
Twelve Months or Longer Fair value
Twelve Months or Longer Unrealized Losses
Total Fair Value	20,357	10,410
Total gross unrealized loss	(185)	(51)
Equity securities [Member]
Amount of securities in an unrealized loss position
Less than Twelve Months Fair Value		976
Less than Twelve Months Unrealized Losses		(133)
Twelve Months or Longer Fair value
Twelve Months or Longer Unrealized Losses
Total Fair Value		976
Total gross unrealized loss		$ (133)