Investments (Amortized Cost and Aggregate Fair Value of Debt Securities, by Contractual Maturity) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Investments [Abstract]
Available-for-sale Securities, Due in one year or less, Amortized Cost	$ 581
Available-for-sale Securities, Due in one year or less, Fair Value	596
Available-for-sale Securities, Due after one year through five years, Amortized Cost	16,278
Available-for-sale Securities, Due after one year through five years, Fair Value	17,785
Available-for-sale Securities, Due after five years through ten years, Amortized Cost	24,896
Available-for-sale Securities, Due after five years through ten years, Fair Value	26,427
Available-for-sale Securities, Due after ten years, Amortized Cost	33,288
Available-for-sale Securities, Due after ten years, Fair Value	34,951
Available-for-sale securities, Amortized Cost	75,043	71,678
Available-for-sale Securities, Fair Value	79,759
Held-to-maturity Securities, Due in one year or less, Amortized Cost	0
Held-to-maturity Securities, Due in one year or less, Fair Value	0
Held-to-maturity Securities, Due after one year through five years, Amortized Cost	384
Held-to-maturity Securities, Due after one year through five years, Fair Value	402
Held-to-maturity Securities, Due after five years through ten years, Amortized Cost	109
Held-to-maturity Securities, Due after five years through ten years, Fair Value	117
Held-to-maturity Securities, Due after ten years, Amortized Cost	821
Held-to-maturity Securities, Due after ten years, Fair Value	894
Held-to-maturity Securities, Amortized Cost	1,314	1,502
Held-to-maturity Securities, Fair Value	$ 1,413	$ 1,609