Fair Value Measurements - Fair value on a recurring basis, the fair value measurements by level within the fair value hierarchy (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Available-for-Sale Portfolio
Securities available for sale	$ 18,363	$ 17,747
Fair Value | Level 2
Available-for-Sale Portfolio
Securities available for sale	18,363	17,747
Fair Value, Measurements, Recurring | Level 1
Available-for-Sale Portfolio
Securities available for sale
Fair Value, Measurements, Recurring | Level 1 | U.S. Government and agency obligations
Available-for-Sale Portfolio
Securities available for sale
Fair Value, Measurements, Recurring | Level 1 | Mortgage-backed securities - residential
Available-for-Sale Portfolio
Securities available for sale
Fair Value, Measurements, Recurring | Level 2
Available-for-Sale Portfolio
Securities available for sale	18,363	17,747
Fair Value, Measurements, Recurring | Level 2 | U.S. Government and agency obligations
Available-for-Sale Portfolio
Securities available for sale	9,508	7,999
Fair Value, Measurements, Recurring | Level 2 | Mortgage-backed securities - residential
Available-for-Sale Portfolio
Securities available for sale	8,855	9,748
Fair Value, Measurements, Recurring | Level 3
Available-for-Sale Portfolio
Securities available for sale
Fair Value, Measurements, Recurring | Level 3 | U.S. Government and agency obligations
Available-for-Sale Portfolio
Securities available for sale
Fair Value, Measurements, Recurring | Level 3 | Mortgage-backed securities - residential
Available-for-Sale Portfolio
Securities available for sale
Fair Value, Measurements, Recurring | Fair Value
Available-for-Sale Portfolio
Securities available for sale	18,363	17,747
Fair Value, Measurements, Recurring | Fair Value | U.S. Government and agency obligations
Available-for-Sale Portfolio
Securities available for sale	9,508	7,999
Fair Value, Measurements, Recurring | Fair Value | Mortgage-backed securities - residential
Available-for-Sale Portfolio
Securities available for sale	$ 8,855	$ 9,748