Edit in JSFiddle

$('.summary').click(function(){
    $(this).parent('.details').children('p').slideToggle();
});
$('.details p').hide();
<div class='details'>
    <div class='summary'>Summary 1</div>
    <p>Details 1.1</p>
    <p>Details 1.2</p>
</div>
<div class='details'>
    <div class='summary'>Summary 2</div>
    <p>Details 2.1</p>
    <p>Details 2.2</p>
</div>
.summary {
    font-weight: bold;
}