Show/hide field with jQuery

$(document).ready(function() {
        var policeInvolvedYes = $('input[name="policeInvolved"][value="yes"]');
        var policeDetailsGroup = $('#policeDetailsGroup');
        var policeDetails = $('#policeDetails');

        function updatePoliceDetailsField() {
            if (policeInvolvedYes.is(':checked')) {
                policeDetailsGroup.show();
                policeDetails.prop('required', true);
            } else {
                policeDetailsGroup.hide();
                policeDetails.prop('required', false);
            }
        }

        policeInvolvedYes.on('change', updatePoliceDetailsField);
        updatePoliceDetailsField();
    });

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<div class="form-group">
        <label>Were Police/Emergency Services involved?</label>
        <div class="radio">
          <label>
            <input type="radio" name="policeInvolved" value="yes"> Yes
          </label>
        </div>
        <div class="radio">
          <label>
            <input type="radio" name="policeInvolved" value="no"> No
          </label>
        </div>
      </div>

        <div id="policeDetailsGroup" style="display: none;">
            <label for="policeDetails">If yes, please specify:</label>
            <input type="text" class="form-control" id="policeDetails" name="policeDetails" placeholder="Enter details">
        </div>