How to get the Idle time for the process

Hi,

How can i get the Idle time for the process.

For Example: If i am using notepad, i need to find the Idle time of that particular Process.

If i am typing the name of that process in the text box (notepad.exe), the Output should be like

this:    (Idle Time:10:30AM )

Please any one help me.

Thanks in advance.