function toggleDetails(elem) {

$(elem).parent().children(':not(.kopf)').toggle();

var toggle_img = $(elem).parent().children(".kopf").css("background-image"); 
if ( toggle_img.search(/plus/i) != -1 ) {
$(elem).parent().children(".kopf").css("background-image", "url('images/cms/aufklapp-minus.gif')");
} else {
$(elem).parent().children(".kopf").css("background-image", "url('images/cms/aufklapp-plus.gif')");
}

}