Get CheckBox Checked ids using JQuery

<script>
    $(document).ready(function() {
        $('#bt_save').click(function() {

            var Contract_Period = '';
            var Campaign_Period = '';
            var Targets = '';
            var chkActuals = '';


            $('input[id="Contract_Period"]').each(function(e) {
                if (this.checked) {
                    Contract_Period = $('#Contract_Period').attr('id');
                }
            });
            $('input[id="Campaign_Period"]').each(function(e) {
                if (this.checked) {
                    Campaign_Period = $('#Campaign_Period').attr('id');
                }
            });

            $('input[id="Targets"]').each(function(e) {
                if (this.checked) {
                    Targets = $('#Targets').attr('id');
                }
            });

            $('input[id="chkActuals"]').each(function(e) {
                if (this.checked) {
                    chkActuals = $('#chkActuals').attr('id');
                }
            });
        });

    });
</script>