{
 "symbol": "ssbox",
 "name": "State Street Institutional Investment Trust - Target Retirement 2020 Fund",
 "filing": {
  "accession": "0001193125-25-048021",
  "doc": "d834955dncsr.htm",
  "period_end": "2024-12-31",
  "display": "STATE STREET INSTITUTIONAL INVESTMENT TRUST  (CIK 0001107414)",
  "ciks": [
   "0001107414"
  ],
  "score": 12.350471
 },
 "how": "ticker",
 "n_bytes": 84223997,
 "verdict": "weak-match",
 "class": "Class K",
 "mean_rel_err": 0.4305,
 "nav_check": {
  "date": "2020-12-31",
  "official": 11.97,
  "local": 12.23,
  "rel": 0.0217,
  "ok": true
 },
 "periods": [
  {
   "period": "current",
   "end": "2024-12-31",
   "official": 0.64,
   "local": 1.146,
   "diff": -0.506,
   "ok": false,
   "unbounded": false
  },
  {
   "period": "fy",
   "end": "2023-12-31",
   "official": 0.57,
   "local": 0.819,
   "diff": -0.249,
   "ok": false,
   "unbounded": false
  },
  {
   "period": "fy",
   "end": "2022-12-31",
   "official": 0.53,
   "local": 1.197,
   "diff": -0.667,
   "ok": false,
   "unbounded": false
  },
  {
   "period": "fy",
   "end": "2021-12-31",
   "official": 0.83,
   "local": 1.457,
   "diff": -0.627,
   "ok": false,
   "unbounded": false
  },
  {
   "period": "fy",
   "end": "2020-12-31",
   "official": 0.19,
   "local": 3.547,
   "diff": -3.357,
   "ok": false,
   "unbounded": true
  }
 ],
 "other_classes": [
  "Class I"
 ]
}