v3.25.2
Shareholder Report
 6 Months Ended
Jun. 30, 2025
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name ELFUN INCOME FUND
Entity Central Index Key 0000717854
Entity Investment Company Type N-1A
Document Period End Date Jun. 30, 2025
C000032333  
Shareholder Report [Line Items]  
Fund Name Elfun Income Fund
Trading Symbol EINFX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about the Elfun Income Fund (the "Fund") for the period of January 1, 2025 through June 30, 2025.
Shareholder Report Annual or Semi-Annual Semi-Annual Shareholder Report
Additional Information [Text Block] You can find additional information about the Fund, including the Prospectus, Statement of Additional Information, financial statements and other information at https://www.ssga.com/us/en/institutional/fund-finder?type=mf . You can also request this information about the Fund by contacting us at 1-800-242-0134.
Additional Information Phone Number 1-800-242-0134
Additional Information Website https://www.ssga.com/us/en/institutional/fund-finder?type=mf 
Expenses [Text Block]

What were the Fund costs for the last six months? (based on a hypothetical $10,000 Investment)

Fund Name
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Elfun Income Fund
$19
0.38%Footnote Reference*
Footnote Description
Footnote*
 Annualized.
Expenses Paid, Amount $ 19
Expense Ratio, Percent 0.38% [1]
AssetsNet $ 125,797,930
Holdings Count | Holding 1,090
InvestmentCompanyPortfolioTurnover 10.00%
Additional Fund Statistics [Text Block]

Key Fund Statistics as of 6/30/2025

  • Total Net Assets$125,797,930
  • Number of Portfolio Holdings1,090
  • Portfolio Turnover Rate10%

 
Holdings [Text Block]

Top Security Types

Asset
%
Corporate Notes
33.1%
Agency Mortgage Backed
29.3%
U.S. Treasuries
27.9%
Short-Term Investments
18.6%
Non-Agency Collateralized Mortgage Obligations
6.2%
Agency Collateralized Mortgage Obligations
0.9%
Municipal Bonds and Notes
0.2%
Asset Backed
0.0%Footnote Reference*
Footnote Description
Footnote*
 Less than 0.05%.
Largest Holdings [Text Block]

Top Ten Holdings

Holdings
%
Uniform Mortgage-Backed Security, TBA, 2.50%, due 07/01/55
3.9%
Uniform Mortgage-Backed Security, TBA, 6.00%, due 07/01/54
3.1%
Uniform Mortgage-Backed Security, TBA, 6.50%, due 07/01/54
3.0%
U.S. Treasury Inflation-Indexed Notes, 1.88%, due 07/15/34
2.8%
Uniform Mortgage-Backed Security, TBA, 2.00%, due 07/01/54
2.8%
Uniform Mortgage-Backed Security, TBA, 3.50%, due 07/01/54
2.5%
U.S. Treasury Notes, 4.30%, due 09/30/25
2.4%
U.S. Treasury Notes, 0.75%, due 01/31/28
2.4%
U.S. Treasury Notes, 4.63%, due 05/31/31
2.3%
Uniform Mortgage-Backed Security, TBA, 3.00%, due 07/01/54
2.1%
[1] Annualized.