Investment Securities - Amortized cost and estimated fair value by contractual maturity of debt securities (Details 1) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Available-for-Sale Amortized Cost
Due in one year or less
Due after one year through five years	$ 1,000
Due after five years through ten years	3,167
Due after ten years	1,910
Sub-total	6,077
Amortized cost	$ 19,194	$ 19,974
Available-for-Sale Fair Value
Due in one year or less
Due after one year through five years	$ 1,001
Due after five years through ten years	3,173
Due after ten years	1,915
Sub-total	6,089
Fair Value	19,284	19,968
Held-to-Maturity Amortized Cost
Due in one year or less	156
Due after one year through five years	2,438
Due after five years through ten years	4,503
Due after ten years	955
Sub-total	8,052
Amortized cost	9,556	12,979
Held-to-Maturity Fair Value
Due in one year or less	158
Due after one year through five years	2,489
Due after five years through ten years	4,614
Due after ten years	1,000
Sub-total	8,261
Fair Value	9,804	13,222
Mortgage-backed securities - residential
Available-for-Sale Amortized Cost
Amortized cost	13,117	13,974
Available-for-Sale Fair Value
Fair Value	13,195	14,000
Held-to-Maturity Amortized Cost
Amortized cost	1,504	1,535
Held-to-Maturity Fair Value
Fair Value	$ 1,543	$ 1,574