I am not sure that expression drill possible in qlikview.
But easiest way to acomplish your task is ,
You can create two chart
1 with total and
2 With detail
Place them on each other and using Property->Layout tab>show it conditionally.
For this you can create one text Object set appropriate action to it.
Place it on Legend showing in chart
and make it transparent so when user click on Total it will change the chart.
Hope It will help you to acheive your task.
Thank you for your reply,but I dont have Total field,I have to calculate it,but as I used it as calculated dimension it wont show the entire month value,it will show only specific month value.
Its okay I got the solution by creating Two charts with a text object,and I have added this text object on the chart by adding action to navigate from chart1 to chart2 and it works fine.