What temperature do you set your thermostat to at night in the winter?

We live in Chicago so it is obviously very cold in the winter. Our heating bill is $300+ in the winter for a 2 bedroom condo and my husband insists on having the heat at close to 70 degrees. I think this is ridiculously high especially due to the cost. He never wears socks and doesn't really like covers. I think he should dress warmer and we should turn the heat down at night...