API Contact.get does not return employer_id, even when speficied as return parameter

{{ $results = civicrm_api3('Contact', 'get', array(
'contact_type' => 'Individual',
'return' => 'display_name, contact_id, current_employer, employer_id',
));
}}

The employer_id attribute is not present in the results, yet it is a column in the DB table.