It works perfectly fine for me. Maybe you're styling your checkbox incorrectly?
jsFiddle
HTML
<input type="checkbox" />
CSS
.idleField {
display:block;
width:100px;
height:100px;
}
JS
$(document).ready(function () {
$('input[type="text"],input[type="password"],select,input[type="submit"],input[type="checkbox"]').addClass("idleField").addClass("idleField");
});
Update
It's working in your jsFiddle, your styles can't applying to the checkbox though. Checkboxes (and radio buttons) are determined by your operating system and can't be styled in the same manner as text boxes for example. Normally styling checkboxes or radio buttons involves hiding the original input and then creating a new div (or a label) and styling that maybe with a pseudo-element.
