| Debt Securities, Available-for-Sale [Table Text Block] | 
    
|   | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  Mortgage-backed   | 
  | 
  | 
  Collateralized   | 
  | 
  | 
  | 
  | 
  | 
 
|   | 
  | 
  U.S. government   | 
  | 
  | 
  Municipal   | 
  | 
  | 
  residential   | 
  | 
  | 
  mortgage   | 
  | 
  | 
  Total available-for-   | 
  | 
 
|   March 31, 2022   | 
  | 
  agency obligations   | 
  | 
  | 
  obligations   | 
  | 
  | 
  obligations   | 
  | 
  | 
  obligations   | 
  | 
  | 
  sale   | 
  | 
 
|   | 
  | 
  (Dollars in thousands)   | 
  | 
 
|   1 year or less   | 
  | 
$ | 
— | 
  | 
  | 
$ | 
650 | 
  | 
  | 
$ | 
— | 
  | 
  | 
$ | 
56 | 
  | 
  | 
$ | 
706 | 
  | 
 
|   1 to 5 years   | 
  | 
  | 
4,814 | 
  | 
  | 
  | 
4,232 | 
  | 
  | 
  | 
28,569 | 
  | 
  | 
  | 
18,853 | 
  | 
  | 
  | 
56,468 | 
  | 
 
|   5 to 10 years   | 
  | 
  | 
10,326 | 
  | 
  | 
  | 
2,619 | 
  | 
  | 
  | 
15,651 | 
  | 
  | 
  | 
12,942 | 
  | 
  | 
  | 
41,538 | 
  | 
 
|   After 10 years   | 
  | 
  | 
— | 
  | 
  | 
  | 
13,253 | 
  | 
  | 
  | 
— | 
  | 
  | 
  | 
1,491 | 
  | 
  | 
  | 
14,744 | 
  | 
 
|   Fair value   | 
  | 
  | 
15,140 | 
  | 
  | 
  | 
20,754 | 
  | 
  | 
  | 
44,220 | 
  | 
  | 
  | 
33,342 | 
  | 
  | 
  | 
113,456 | 
  | 
 
|   Gross unrealized gains   | 
  | 
  | 
— | 
  | 
  | 
  | 
84 | 
  | 
  | 
  | 
10 | 
  | 
  | 
  | 
8 | 
  | 
  | 
  | 
102 | 
  | 
 
|   Gross unrealized losses   | 
  | 
  | 
(658 | 
) | 
  | 
  | 
(1,230 | 
) | 
  | 
  | 
(2,579 | 
) | 
  | 
  | 
(1,991 | 
) | 
  | 
  | 
(6,458 | 
) | 
 
|   Amortized cost   | 
  | 
$ | 
15,798 | 
  | 
  | 
$ | 
21,900 | 
  | 
  | 
$ | 
46,789 | 
  | 
  | 
$ | 
35,325 | 
  | 
  | 
$ | 
119,812 | 
  | 
 
 
    
|   | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  Mortgage-backed   | 
  | 
  | 
  Collateralized   | 
  | 
  | 
  | 
  | 
  | 
 
|   | 
  | 
  U.S. government   | 
  | 
  | 
  Municipal   | 
  | 
  | 
  residential   | 
  | 
  | 
  mortgage   | 
  | 
  | 
  Total available-for-   | 
  | 
 
|   December 31, 2021   | 
  | 
  agency obligations   | 
  | 
  | 
  obligations   | 
  | 
  | 
  obligations   | 
  | 
  | 
  obligations   | 
  | 
  | 
  sale   | 
  | 
 
|   | 
  | 
  (Dollars in thousands)   | 
  | 
 
|   1 year or less   | 
  | 
$ | 
— | 
  | 
  | 
$ | 
1,631 | 
  | 
  | 
$ | 
356 | 
  | 
  | 
$ | 
1,064 | 
  | 
  | 
$ | 
3,051 | 
  | 
 
|   1 to 5 years   | 
  | 
  | 
5,587 | 
  | 
  | 
  | 
3,941 | 
  | 
  | 
  | 
29,375 | 
  | 
  | 
  | 
16,097 | 
  | 
  | 
  | 
55,000 | 
  | 
 
|   5 to 10 years   | 
  | 
  | 
4,466 | 
  | 
  | 
  | 
2,244 | 
  | 
  | 
  | 
12,417 | 
  | 
  | 
  | 
11,976 | 
  | 
  | 
  | 
31,103 | 
  | 
 
|   After 10 years   | 
  | 
  | 
— | 
  | 
  | 
  | 
10,184 | 
  | 
  | 
  | 
— | 
  | 
  | 
  | 
1,612 | 
  | 
  | 
  | 
11,796 | 
  | 
 
|   Fair value   | 
  | 
  | 
10,053 | 
  | 
  | 
  | 
18,000 | 
  | 
  | 
  | 
42,148 | 
  | 
  | 
  | 
30,749 | 
  | 
  | 
  | 
100,950 | 
  | 
 
|   Gross unrealized gains   | 
  | 
  | 
73 | 
  | 
  | 
  | 
423 | 
  | 
  | 
  | 
259 | 
  | 
  | 
  | 
279 | 
  | 
  | 
  | 
1,034 | 
  | 
 
|   Gross unrealized losses   | 
  | 
  | 
(78 | 
) | 
  | 
  | 
(14 | 
) | 
  | 
  | 
(612 | 
) | 
  | 
  | 
(443 | 
) | 
  | 
  | 
(1,147 | 
) | 
 
|   Amortized cost   | 
  | 
$ | 
10,058 | 
  | 
  | 
$ | 
17,591 | 
  | 
  | 
$ | 
42,501 | 
  | 
  | 
$ | 
30,913 | 
  | 
  | 
$ | 
101,063 | 
  | 
 
 
   
 | 
| Debt Securities, Available-for-Sale, Unrealized Loss Position, Fair Value [Table Text Block] | 
    
|   | 
  | 
  Less than 12 Months   | 
  | 
  | 
  12 Months or Longer   | 
  | 
  | 
  Total   | 
  | 
 
|   | 
  | 
  (Dollars in thousands)   | 
  | 
 
|   | 
  | 
  Fair   | 
  | 
  | 
  Unrealized   | 
  | 
  | 
  Fair   | 
  | 
  | 
  Unrealized   | 
  | 
  | 
  Fair   | 
  | 
  | 
  Unrealized   | 
  | 
 
|   | 
  | 
  Value   | 
  | 
  | 
  Losses   | 
  | 
  | 
  Value   | 
  | 
  | 
  Losses   | 
  | 
  | 
  Value   | 
  | 
  | 
  Losses   | 
  | 
 
|   March 31, 2022   | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
 
|   U.S. government agency obligations   | 
  | 
$ | 
12,652 | 
  | 
  | 
$ | 
641 | 
  | 
  | 
$ | 
1,094 | 
  | 
  | 
$ | 
17 | 
  | 
  | 
$ | 
13,746 | 
  | 
  | 
$ | 
658 | 
  | 
 
|   Municipal obligations   | 
  | 
  | 
12,235 | 
  | 
  | 
  | 
1,210 | 
  | 
  | 
  | 
233 | 
  | 
  | 
  | 
20 | 
  | 
  | 
  | 
12,468 | 
  | 
  | 
  | 
1,230 | 
  | 
 
|   Mortgage-backed residential obligations   | 
  | 
  | 
30,194 | 
  | 
  | 
  | 
1,536 | 
  | 
  | 
  | 
11,238 | 
  | 
  | 
  | 
1,043 | 
  | 
  | 
  | 
41,432 | 
  | 
  | 
  | 
2,579 | 
  | 
 
|   Collateralized mortgage obligations   | 
  | 
  | 
16,785 | 
  | 
  | 
  | 
973 | 
  | 
  | 
  | 
10,827 | 
  | 
  | 
  | 
1,018 | 
  | 
  | 
  | 
27,612 | 
  | 
  | 
  | 
1,991 | 
  | 
 
|   Total   | 
  | 
$ | 
71,866 | 
  | 
  | 
$ | 
4,360 | 
  | 
  | 
$ | 
23,392 | 
  | 
  | 
$ | 
2,098 | 
  | 
  | 
$ | 
95,258 | 
  | 
  | 
$ | 
6,458 | 
  | 
 
|   December 31, 2021   | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
  | 
 
|   U.S. government agency obligations   | 
  | 
$ | 
4,020 | 
  | 
  | 
$ | 
62 | 
  | 
  | 
$ | 
1,105 | 
  | 
  | 
$ | 
16 | 
  | 
  | 
$ | 
5,125 | 
  | 
  | 
$ | 
78 | 
  | 
 
|   Municipal obligations   | 
  | 
  | 
2,399 | 
  | 
  | 
  | 
8 | 
  | 
  | 
  | 
247 | 
  | 
  | 
  | 
6 | 
  | 
  | 
  | 
2,646 | 
  | 
  | 
  | 
14 | 
  | 
 
|   Mortgage-backed residential obligations   | 
  | 
  | 
26,540 | 
  | 
  | 
  | 
535 | 
  | 
  | 
  | 
2,781 | 
  | 
  | 
  | 
77 | 
  | 
  | 
  | 
29,321 | 
  | 
  | 
  | 
612 | 
  | 
 
|   Collateralized mortgage obligations   | 
  | 
  | 
16,715 | 
  | 
  | 
  | 
338 | 
  | 
  | 
  | 
4,386 | 
  | 
  | 
  | 
105 | 
  | 
  | 
  | 
21,101 | 
  | 
  | 
  | 
443 | 
  | 
 
|   Total   | 
  | 
$ | 
49,674 | 
  | 
  | 
$ | 
943 | 
  | 
  | 
$ | 
8,519 | 
  | 
  | 
$ | 
204 | 
  | 
  | 
$ | 
58,193 | 
  | 
  | 
$ | 
1,147 | 
  | 
 
 
   
 |