Regulatory Capital (Details) - USD ($)
$ in Thousands |
Mar. 31, 2018 |
Dec. 31, 2017 |
| Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |
|
|
| Total capital (to risk-weighted assets) |
$ 412,639
|
$ 426,057
|
| Tier I capital (to risk-weighted assets) |
|
411,980
|
| Common Equity Tier 1 Capital (to risk-weighted assets) |
399,449
|
411,980
|
| Tier I capital (to average assets) |
$ 399,449
|
$ 411,980
|
| Total capital (to risk-weighted assets) Ratio |
29.96%
|
30.75%
|
| Tier I capital (to risk-weighted assets) Ratio |
|
29.74%
|
| Common Equity Tier 1 capital (to risk-weighted assets) Ratio |
29.00%
|
29.74%
|
| Tier I capital (to average assets) Ratio |
22.31%
|
22.43%
|
| Total capital (to risk-weighted assets), For Capital Adequacy Purposes |
$ 110,202
|
$ 110,829
|
| Tier I capital (to risk-weighted assets), For Capital Adequacy Purposes |
|
83,122
|
| Common Equity Tier I capital (to risk weighted assets), For Capital Adequacy Purposes |
61,988
|
62,341
|
| Tier I capital (to average assets), For Capital Adequacy Purposes |
$ 71,612
|
$ 73,481
|
| Total capital (to risk-weighted assets), For Capital Adequacy Ratio |
8.00%
|
8.00%
|
| Tier I capital (to risk-weighted assets), For Capital Adequacy Ratio |
|
6.00%
|
| Common Equity Tier I capital ( to risk-weighted), For Capital Adequacy Ratio |
4.50%
|
4.50%
|
| Tier I capital (to average assets), For Capital Adequacy Ratio |
4.00%
|
4.00%
|
| Total capital (to risk-weighted assets), Minimum Capital Adequacy with Capital Buffer |
$ 136,030
|
$ 128,146
|
| Tier I capital (to risk weighted assets), Minimum Capital Adequacy with Capital Buffer |
|
100,439
|
| Common Equity Tier I capital (to risk weighted assets) Minimum Capital Adequacy with Capital Buffer |
$ 87,817
|
$ 79,658
|
| Total capital (to risk-weighted assets), Minimum Capital Adequacy with Capital Buffer Ratio |
9.875%
|
9.25%
|
| Tier I capital (to risk weighted assets), Minimum Capital Adequacy with Capital Buffer Ratio |
|
7.25%
|
| Common Equity Tier I capital (to risk weighted), Minimum Capital Adequacy with Capital Buffer Ratio |
6.375%
|
5.75%
|
| Waterstone Bank [Member] |
|
|
| Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |
|
|
| Total capital (to risk-weighted assets) |
$ 383,288
|
$ 400,792
|
| Tier I capital (to risk-weighted assets) |
370,098
|
386,715
|
| Common Equity Tier 1 Capital (to risk-weighted assets) |
370,098
|
386,715
|
| Tier I capital (to average assets) |
370,098
|
386,715
|
| State of Wisconsin (to total assets) |
$ 370,098
|
$ 386,715
|
| Total capital (to risk-weighted assets) Ratio |
27.85%
|
28.93%
|
| Tier I capital (to risk-weighted assets) Ratio |
26.89%
|
27.92%
|
| Common Equity Tier 1 capital (to risk-weighted assets) Ratio |
26.89%
|
27.92%
|
| Tier I capital (to average assets) Ratio |
20.67%
|
21.10%
|
| State of Wisconsin (to total assets) Ratio |
20.17%
|
21.44%
|
| Total capital (to risk-weighted assets), For Capital Adequacy Purposes |
$ 110,096
|
$ 110,812
|
| Tier I capital (to risk-weighted assets), For Capital Adequacy Purposes |
82,572
|
83,109
|
| Common Equity Tier I capital (to risk weighted assets), For Capital Adequacy Purposes |
61,929
|
62,332
|
| Tier I capital (to average assets), For Capital Adequacy Purposes |
71,612
|
73,304
|
| State of Wisconsin (to total assets), For Capital Adequacy Purposes |
$ 110,101
|
$ 108,243
|
| Total capital (to risk-weighted assets), For Capital Adequacy Ratio |
8.00%
|
8.00%
|
| Tier I capital (to risk-weighted assets), For Capital Adequacy Ratio |
6.00%
|
6.00%
|
| Common Equity Tier I capital ( to risk-weighted), For Capital Adequacy Ratio |
4.50%
|
4.50%
|
| Tier I capital (to average assets), For Capital Adequacy Ratio |
4.00%
|
4.00%
|
| State of Wisconsin (to total assets), For Capital Adequacy Ratio |
6.00%
|
6.00%
|
| Total capital (to risk-weighted assets), Minimum Capital Adequacy with Capital Buffer |
$ 135,899
|
$ 128,127
|
| Tier I capital (to risk weighted assets), Minimum Capital Adequacy with Capital Buffer |
108,375
|
100,424
|
| Common Equity Tier I capital (to risk weighted assets) Minimum Capital Adequacy with Capital Buffer |
$ 87,732
|
$ 79,646
|
| Total capital (to risk-weighted assets), Minimum Capital Adequacy with Capital Buffer Ratio |
9.875%
|
9.25%
|
| Tier I capital (to risk weighted assets), Minimum Capital Adequacy with Capital Buffer Ratio |
7.875%
|
7.25%
|
| Common Equity Tier I capital (to risk weighted), Minimum Capital Adequacy with Capital Buffer Ratio |
6.375%
|
5.75%
|
| Total capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions |
$ 137,619
|
$ 138,515
|
| Tier I capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions |
110,096
|
110,812
|
| Common Equity Tier I capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions |
89,453
|
90,035
|
| Tier I capital (to average assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions |
$ 89,516
|
$ 91,630
|
| Total capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Ratio |
10.00%
|
10.00%
|
| Tier I capital (to risk-weighted assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Ratio |
8.00%
|
8.00%
|
| Common Equity Tier I capital (to risk-weighted) , To Be Well-Capitalized Under Prompt Corrective Action Provisions Ratio |
6.50%
|
6.50%
|
| Tier I capital (to average assets), To Be Well-Capitalized Under Prompt Corrective Action Provisions Ratio |
5.00%
|
5.00%
|
| Consolidated Waterstone Financial, Inc. [Member] |
|
|
| Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |
|
|
| Tier I capital (to risk-weighted assets) |
$ 399,449
|
|
| Tier I capital (to risk-weighted assets) Ratio |
29.00%
|
|
| Tier I capital (to risk-weighted assets), For Capital Adequacy Purposes |
$ 82,651
|
|
| Tier I capital (to risk-weighted assets), For Capital Adequacy Ratio |
6.00%
|
|
| Tier I capital (to risk weighted assets), Minimum Capital Adequacy with Capital Buffer |
$ 108,480
|
|
| Tier I capital (to risk weighted assets), Minimum Capital Adequacy with Capital Buffer Ratio |
7.875%
|
|