I agree with Ophir and Chris. My feeling is that it is purely a serial number / unique click ID, which only opens up its secrets when the Analytics and Adwords systems talk to each other behind the scenes.
Knowing this, I'd recommend looking at the referring URL and pulling as much as possible from this to use in your back end click tracking setup.
For example, I live in NZ, and am using Firefox. This is a search from the Firefox Google toolbar for "stack overflow":
http://www.google.co.nz/search?q=stack+overflow&ie=utf-8&oe=utf-8&aq=t&client=firefox-a&rlz=1R1GGLL_en-GB
You can see that: a) im using .NZ domain, b) my keyword "stack+overflow", c) im running firefox.
Finally, if you also stash the full landing page URL, you can store the GCLID, which will tell you the visitor came from paid, whereas if it doesn't have a GCLID, then the user must have come from natural search (if URL tagging is enabled of course).
This would theoretically allow you to then search for the keyword in your campaign, and figure out which adgroup them came from. Knowing the creative would probably be impossible though, unless you split test your landing URLs or tag them somehow.