Polymer: Detect click outside of custom element

I have a custom element and would like to detect clicks outside of it. For example

<dom-module id="simple-element">



<style>
  </style>

  <template>
    <content></content>
  </template>

</dom-module>

<script>
  (function() {
    Polymer({
      is: 'simple-element',
      listeners: {
        'tap': 'regularTap'
      },
      regularTap: function() {
        console.log("i was tapped");
      }
    });
  })();
</script>

Is there an event where I can listen to which will tell me when user has clicked outside of the element? Thanks.