Can i get With out _id array when using group aggregate in mongodb?

db.case_details.aggregate( [
  {
    $facet: {
      "status_counts": [{"$group" : {_id:{source:"$source",status:"$status"}, count:{$sum:1}}}],
      "Priority_counts": [{$match:{"status":{$ne:"Closed"}}},{"$group" : {_id:{source:"$source",status:"$priority"}, count:{$sum:1}}}] }}])

==================================================================

From the above query I got result like below:

{ status_counts: 
   [ { _id: { status: 'Open' }, count: 696 },
     { _id: { status: 'Closed' }, count: 59662 },
     { _id: { status: 'Pending' }, count: 4039 } ],
  Priority_counts: 
   [ { _id: { status: 'Low' }, count: 11 },
     { _id: { status: 'Escalated' }, count: 4722 },
     { _id: { status: 'Medium' }, count: 1 },
     { _id: { status: 'High' }, count: 1 } ] }

==================================================

Is there any chance to get result as Like:

{Open:696,Pending:4039 ,Closed:59662, Low:11,Escalated:4722,Medium:1,High:1}