You can do this yourself: 1) save the detail file periodically as a
different name, 2) create a matching template in any flat-file database, 3)
import the saved detail file, 4) delete the unnecessary fields, 5) parse the
remaining fields to clean them up, 6) design reports that subtract
start-stop times from matching session IDs and other items you want. Then,
do this all over again for your next accounting period, and create a method
for multi-period consolidation.
Or, you can just buy Emerald (www.emerald.iea.com).