v3.26.1
Shareholder Report
 6 Months Ended
Jun. 30, 2026
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, 2026
Shareholder Report Annual or Semi-Annual Semi-Annual Shareholder Report
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, 2026 through June 30, 2026.
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 www.ssga.com/us/en/institutional/fund-finder?tab=documents&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 www.ssga.com/us/en/institutional/fund-finder?tab=documents&type=mf
Expenses [Text Block]

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

Table Summary
Fund Name
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Elfun Income Fund
$18
0.37%Footnote Reference*
Footnote Description
Footnote*
 Annualized.
Expenses Paid, Amount $ 18
Expense Ratio, Percent 0.37% [1]
AssetsNet $ 110,214,409
Holdings Count | Holding 1,040
InvestmentCompanyPortfolioTurnover 16.00%
Additional Fund Statistics [Text Block]

Key Fund Statistics as of 6/30/2026

  • Total Net Assets$110,214,409
  • Number of Portfolio Holdings1,040
  • Portfolio Turnover Rate16%
Holdings [Text Block]

Top Security Types

Table Summary
Assets
%
U.S. Treasuries
27.9%
Corporate Notes
27.9%
Agency Mortgage Backed
24.0%
Short-Term Investments
17.2%
Non-Agency Collateralized Mortgage Obligations
12.7%
Asset Backed
1.7%
Agency Collateralized Mortgage Obligations
1.0%
Municipal Bonds and Notes
0.2%
Largest Holdings [Text Block]

Top Ten Holdings

Table Summary
Holdings
%
Uniform Mortgage-Backed Security, TBA, 2.50%, due 07/01/56
4.4%
U.S. Treasury Notes, 3.88%, due 07/31/27
3.9%
U.S. Treasury Notes, 3.50%, due 10/31/27
3.8%
Uniform Mortgage-Backed Security, TBA, 6.00%, due 07/01/56
3.5%
U.S. Treasury Bonds, 4.75%, due 08/15/55
2.5%
Uniform Mortgage-Backed Security, TBA, 3.00%, due 07/01/56
2.4%
U.S. Treasury Notes, 3.88%, due 04/30/30
2.4%
U.S. Treasury Bonds, 4.38%, due 08/15/43
2.1%
Bank, Class A4, 3.18%, due 09/15/60
2.1%
Federal National Mortgage Association, 3.50%, due 07/01/47
2.0%
[1] Annualized.