Radio box, get the checked value [iCheck]

Basic radio box

<div class="adv_filter">
    <li>
        <input type="radio" name="letter_type" data-custom="Text" value="0"> Text</li>
    </li>
        <li>
            <input type="radio" name="letter_type" data-custom="Text" value="0"> Text</li>
    </li>
</div>

iCheck transformation

<!-- iCheck output format
<div class="adv_filter">
    <li>
        <div class="iradio_square-orange checked" aria-checked="true" aria-disabled="false" style="position: relative;"><input type="radio" name="letter_type" data-custom="Text" value="0" style="position: absolute; top: -20%; left: -20%; display: block; width: 140%; height: 140%; margin: 0px; padding: 0px; border: 0px; opacity: 0; background: rgb(255, 255, 255);"><ins class="iCheck-helper" style="position: absolute; top: -20%; left: -20%; display: block; width: 140%; height: 140%; margin: 0px; padding: 0px; border: 0px; opacity: 0; background: rgb(255, 255, 255);"></ins></div> Text</li>

        <li>
            <div class="iradio_square-orange" aria-checked="false" aria-disabled="false" style="position: relative;"><input type="radio" name="letter_type" data-custom="Text" value="0" style="position: absolute; top: -20%; left: -20%; display: block; width: 140%; height: 140%; margin: 0px; padding: 0px; border: 0px; opacity: 0; background: rgb(255, 255, 255);"><ins class="iCheck-helper" style="position: absolute; top: -20%; left: -20%; display: block; width: 140%; height: 140%; margin: 0px; padding: 0px; border: 0px; opacity: 0; background: rgb(255, 255, 255);"></ins></div> Text</li>

</div> -->

As you see the checked is attached to the div..

    $(document).ready(function () {
        $('input').iCheck({
            checkboxClass: 'icheckbox_square-orange',
            radioClass: 'iradio_square-orange',
            increaseArea: '20%' // optional
        });
        $("li").on("click", "input", function () {
            var val = $(this).val();
            //updateDataGrid(val);
            alert(val);
        });

    });

Question and description

Provided javascript code worked properly before adding the icheck plugin, I am wondering how to get the same result in the icheck plugin. Its simple, on radio click it stores the value in variable later its passed further to functions.

Live example : http://jsfiddle.net/9ypwjvt4/

iCheck : http://fronteed.com/iCheck/