It is so much worse for the engine to do that thou. Anything over 10 minutes is considered excessive by Cummins and not recommended, at most 3-5 minutes is all Cummins wants. It's cold, but use a block heater and save the wear and tear and wasted diesel $$.
With the way dealerships have been treating idle time on the 6.7 it's not worth it for warranty purposes either.
Around 100 minutes of block heater operation with a winter front is adequate, even on 0°F and colder days to get the block above 80°F.
Too much money for me.
While $1.50/day doesn't sound like much it would have been a 67% increase in my power consumption last month to have the truck plugged in 24/7.
At anything under minus 20C I find that the windows will fog up or the frost is not even close to being melted off the windshield(-45C rated windshield fluid just sits on the frost) . Seeing where you are going justifies the idle time. I don't like it either, but sometimes there is no choice.