You can use following code to define column of same height by providing display layout as table, table-cell.
Define these CSS classes
.container-sm-height 
{
  display: table;
  padding-left:0px;
  padding-right:0px;
}
.row-sm-height 
{
   display: table;
   table-layout: fixed;
   height: 100%;
}
.col-sm-height 
{
  display: table-cell;
  float: none;
  height: 100%;
}
For Small devices use this media query
@media (min-width: 480px) 
 {
 .row-xs-height {
  display: table;
  table-layout: fixed;
  height: 100%;
  width: 100%;
 }
.col-xs-height {
  display: table-cell;
  float: none;
  height: 100%;
 }
}
Now Apply these classes in your HTML structure as following
 <body>
    <div class="row container-fluid row-sm-height">
        <row class="col-sm-3 col-sm-height" id="sidebar">
            <!--your code-->
        </row>
        <row class="col-sm-9 col-sm-height">
            <!--Your code-->
        </row>
    </div>
</body>