Which government workers will be furloughed?

Short of a Christmas miracle, parts of the federal government will shut down at midnight tonight.  Some agencies like the Departments of Defense and Education will face no furloughs because their budgets have already been approved.  And not everyone at the other agencies will face furloughs.  The breakdown looks like this, from the Washington Post,

Department of Housing and Urban Development is expected to shut down but not until January when 95% of their employees will be sent home.

We need to remember that Congress always votes to pay furloughed employees retroactively once they begin work again.  So this is really an unexpected paid vacation for some federal workers.