was your agreement time and material? did you discuss markup?
Only time I saw that request was with a sevice contract for a town - bill at x amount/hr from time you arrive to time you pull away. Material + %
You bid the job and filled in the dollar amount and mark up % - low guy gets the contract - you had to send in with your bill a certifed payroll sheet with supply house slips.
if it is a contract for a set amount I would never give them the breakdown.
if it was a loose agreement on t & m - then you might have a bit of an issue with the owner wanting to dispute your charges - PITA - if you fluffed the bill be sure you include travel time, stock house runs, office billing time, and mark up on material - you can try to make up some hours on that.