Don't do it. A detailed quote, showing labor and materials, is a valuable document. It's the rough draft of a project plan, and you should not give it away.
The only real reason a customer asks for these numbers is to shop your quote around to other contractors, often a CraigsList guy (or other lowballer) who doesn't have the knowledge or skills to measure, choose materials, do takeoff, or estimate time. A materials takeoff and estimate of time is solid gold for those guys.
This request doesn't allow you to quote by a standard rate or other rule of thumb, either.
If I've done the numbers, and I have some reason to share some bit of them with a homeowner (some material is super expensive, for example), I never leave the paperwork with the customer even for a moment. In one case a husband asked me to explain a detail in another room; on a hunch I turned around and went back to the kitchen, and found his wife clicking away at my spreadsheet with her smartphone camera. They were a nice academic/professional couple.
When a customer asks, I tell them that it's a significant part of my project plan, that it's valuable, and that I can't give it away.
I used to give detailed breakdowns, but I've stopped. I now waste less time on those leads, and I get awarded more jobs - those people come back when they find out that they can't get a firm price from the CraigsList guy, if they can't give him my detailed quote.
Don't do it.