Only show sidebar when subpages

Hey there

I am making my own custom theme for wordpress but I have stumbled upon a little problem.

I want to make a sidebar which always shows the subpages of the parent page but if a parent page has no subpages then the sidebar needs to “dissapear” (No div) so my content can take the full page width.

How am I able to achieve this?

My sidebar code is as follow:

<div id="sidebar">
    <ul>
        <li>
            <div style="clear: both;">&nbsp;</div>
        </li>
        <li>
            <?php
		if(!$post->post_parent){
		// will display the subpages of this top level page
		$children = wp_list_pages("title_li=&child_of=".$post->ID."&echo=0");
		}else{
		// diplays only the subpages of parent level
	        //$children = wp_list_pages("title_li=&child_of=".$post->post_parent."&echo=0");

		if($post->ancestors)
					{
		// now you can get the the top ID of this page
	        // wp is putting the ids DESC, thats why the top level ID is the last one
		$ancestors = end($post->ancestors);
		$children = wp_list_pages("title_li=&child_of=".$ancestors."&echo=0");
		// you will always get the whole subpages list
				    }
				}

				if ($children) { ?>
            <ul>
                <?php echo $children; ?>
            </ul>
            <?php } ?>
        </li>
        <li> </li>
    </ul>
</div>

As you see, my current code only gives me the subpages when they exist but doesn’t let the sidebar div “dissapear” when there are no subpages.

Thanks in advance.

Greetings dragongamer54