I have, since completing my PhD (in pure mathematics), worked in both non-academic and post-doc positions. I am brushing up my CV, and I would like some advice as to how one should detail non-academic work. My non-academic work has been quantitative, but otherwise entirely unrelated to my field of academic expertise, so my gained skills (in eg statistical packages) are of no use to the purely research position I am aiming to apply for.
Simply list in the section about employment who you worked for. The places you apply for may ignore this if they so choose, but at least you can document that you were working during this time and were not, as one could be tempted to speculate, in jail, unemployed, or homeless.
But then, it may also be that the people who look at your application think that it is quite beneficial to the program to hire someone who has seen other parts of the world, whether or not you learned specific tasks and skills there that are useful for your postdoc work.