jq – big JSON object transform only subarray of objects

I am trying to transform this JSON object:

{
  "id_1": {},
  "id_2": {
    "sys": "S",
    "details": [
      {
        "detail": "S1",
        "index": 0
      },
      {
        "detail": " ",
        "index": 1
      },
      {
        "detail": " ",
        "index": 2
      },
      {
        "detail": " ",
        "index": 3
      },
      {
        "detail": " ",
        "index": 4
      }
    ],
    "color": "Grey"
  },
  "id_3": {
    "sys": "A",
    "details": [
      {
        "detail": "240",
        "index": 0
      },
      {
        "detail": "63",
        "index": 1
      },
      {
        "detail": "70",
        "index": 2
      },
      {
        "detail": " ",
        "index": 3
      },
      {
        "detail": " ",
        "index": 4
      }
    ],
    "color": "White"
  },
  "id_4": {},
  "id_5": {
    "sys": "G",
    "details": [
      {
        "detail": "266",
        "index": 0
      },
      {
        "detail": "G",
        "index": 1
      },
      { 
        "detail": "1",
        "index": 2
      },
      {
        "detail": " ",
        "index": 3
      },
      {
        "detail": " ",
        "index": 4
      } 
    ],
    "color": "Red"
  }     
}

into that one:

{
  "id_1": {},
  "id_2": {
    "sys": "S",
    "details": ["S1"],
    "color": "Grey",
  },
  "id_3": {
    "sys": "A",
    "details": ["240","63","70"],
    "color": "White",
  },
  "id_4": {},
  "id_5": {
    "sys": "G",
    "details": ["266", "G", "1"],
    "color": "Red",
  }
}

There are also empty objects in the outer object that should be remained. Only the key details should be transformed, others should be kept.

Could not achive to create any valid query with map nor with select. The only valid jq I have created so far: .[]? | [.details[]? | select(.detail != " ")] | .[] .detail, but only results the details strings…

>Solution :

Here is one way:

map_values(
  select(has("details")) .details |=
    map(.detail | select(. != " "))
)

^{Online demo}