My first suggestion would be to contact the local county (or city or ?) authorities & register a complaint. Not only is idling illegal, but in most jurisdictions you can't even have a commercial vehicle in a residential neighborhood, although this depends on the tolerance level of the neighborhood.
It's either a company truck or his own rig & you can look up the name that's on the side of the truck and/or trailer. If it's a bigger company they'll probably do something if you complain but if it's his rig or some jackleg outfit, it'll be a wasted effort. When calling, I'd suggest shielding your name and # to prevent repercussions. It can happen.
There's the possibility it's a reefer unit like Albert mentioned & if that's the case, there's no way the load can stay cool (or warm) w/o the reefer unit running, which is a small diesel located either on the top front of the trailer or under the middle of the trailer. There can be as much as 45k lbs. of product inside & if it goes bad, either the driver or the company has to pay for it, so they'll do whatever it takes to keep it at the proper temp.
