Investment Securities (Investments' Gross Unrealized Losses and Fair Value Aggregated by Investment Category and Length of Time in Continuous Unrealized Loss Position) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	$ 37,885	$ 16,844
Less than 12 Months Gross Unrealized Losses	402	80
12 Months or Longer Fair Value	336	194
12 Months or Longer Gross Unrealized Losses	5,806	5,881
Total Fair Value	38,221	17,038
Total Gross Unrealized Losses	6,208	5,961
State and municipal
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	10,702	4,524
Less than 12 Months Gross Unrealized Losses	123	19
Total Fair Value	10,702	4,524
Total Gross Unrealized Losses	123	19
U.S. Government-sponsored mortgage-backed securities
Investments, Unrealized Loss Position [Line Items]
Less than 12 Months Fair Value	27,183	12,320
Less than 12 Months Gross Unrealized Losses	279	61
Total Fair Value	27,183	12,320
Total Gross Unrealized Losses	279	61
Corporate obligations
Investments, Unrealized Loss Position [Line Items]
12 Months or Longer Fair Value	336	194
12 Months or Longer Gross Unrealized Losses	5,806	5,881
Total Fair Value	336	194
Total Gross Unrealized Losses	$ 5,806	$ 5,881