Shareholders' equity and regulatory matters (Details) - USD ($)
$ in Thousands |
Sep. 30, 2017 |
Dec. 31, 2016 |
| Leverage ratio (Tier 1 capital to average assets), Ratio [Abstract] |
|
|
| For Capital Adequacy Purposes (in percentage) |
4.00%
|
|
| Common equity (Tier 1 risk based capital to risk weighted assets), Ratio [Abstract] |
|
|
| For Capital Adequacy Purposes (in percentage) |
7.00%
|
|
| Subsidiaries [Member] |
|
|
| Total capital (to risk-weighted assets), Amount [Abstract] |
|
|
| Actual Amount |
$ 46,308
|
$ 49,225
|
| For Capital Adequacy Purposes |
26,040
|
25,693
|
| To be Well Capitalized Amount |
$ 32,550
|
$ 32,117
|
| Total capital (to risk-weighted assets), Ratio [Abstract] |
|
|
| Actual Ratio (in percentage) |
14.23%
|
15.33%
|
| For Capital Adequacy Purposes (in percentage) |
8.00%
|
8.00%
|
| To be Well Capitalized (in percentage) |
10.00%
|
10.00%
|
| Tier 1 capital (to risk-capital to average assets), Amount [Abstract] |
|
|
| Actual Amount |
$ 43,065
|
$ 45,852
|
| For Capital Adequacy Purposes |
19,530
|
12,847
|
| To be Well Capitalized Amount |
$ 26,040
|
$ 19,270
|
| Tier 1 capital (to risk-capital to average assets), Ratio [Abstract] |
|
|
| Actual Ratio (in percentage) |
13.23%
|
14.28%
|
| For Capital Adequacy Purposes (in percentage) |
6.00%
|
4.00%
|
| To be Well Capitalized (in percentage) |
8.00%
|
6.00%
|
| Leverage ratio (Tier 1 capital to average assets), Amount [Abstract] |
|
|
| Actual Amount |
$ 43,065
|
$ 45,852
|
| For Capital Adequacy Purposes |
18,299
|
17,523
|
| To be Well Capitalized Amount |
$ 22,873
|
$ 21,903
|
| Leverage ratio (Tier 1 capital to average assets), Ratio [Abstract] |
|
|
| Actual Ratio (in percentage) |
9.51%
|
10.47%
|
| For Capital Adequacy Purposes (in percentage) |
4.00%
|
4.00%
|
| To be Well Capitalized (in percentage) |
5.00%
|
5.00%
|
| Common equity (Tier 1 risk based capital to risk weighted assets), Amount [Abstract] |
|
|
| Actual Amount |
$ 43,065
|
$ 45,852
|
| For Capital Adequacy Purposes |
14,648
|
14,452
|
| To be Well Capitalized Amount |
$ 21,158
|
$ 20,876
|
| Common equity (Tier 1 risk based capital to risk weighted assets), Ratio [Abstract] |
|
|
| Actual Ratio (in percentage) |
13.23%
|
14.28%
|
| For Capital Adequacy Purposes (in percentage) |
4.50%
|
4.50%
|
| To be Well Capitalized (in percentage) |
6.50%
|
6.50%
|