Investments (Amortized Cost and Aggregate Fair Value of Debt Securities, by Contractual Maturity) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Investments [Abstract]
Available-for-sale Securities, Due in one year or less, Amortized Cost	$ 2,830
Available-for-sale Securities, Due in one year or less, Fair Value	2,873
Available-for-sale Securities, Due after one year through five years, Amortized Cost	14,979
Available-for-sale Securities, Due after one year through five years, Fair Value	14,933
Available-for-sale Securities, Due after five years through ten years, Amortized Cost	33,246
Available-for-sale Securities, Due after five years through ten years, Fair Value	33,644
Available-for-sale Securities, Due after ten years, Amortized Cost	41,217
Available-for-sale Securities, Due after ten years, Fair Value	41,247
Available-for-sale securities, Amortized Cost	92,272	$ 92,837
Available-for-sale Securities, Fair Value	92,697
Held-to-maturity Securities, Due in one year or less, Amortized Cost	13
Held-to-maturity Securities, Due in one year or less, Fair Value	13
Held-to-maturity Securities, Due after one year through five years, Amortized Cost	9
Held-to-maturity Securities, Due after one year through five years, Fair Value	9
Held-to-maturity Securities, Due after five years through ten years, Amortized Cost	75
Held-to-maturity Securities, Due after five years through ten years, Fair Value	82
Held-to-maturity Securities, Due after ten years, Amortized Cost	1,705
Held-to-maturity Securities, Due after ten years, Fair Value	1,731
Held-to-maturity Securities, Amortized Cost	1,802	1,890
Held-to-maturity Securities, Fair Value	$ 1,835	$ 1,930