v3.26.1
S000012717 [Member] Average Annual Total Returns
12 Months Ended 60 Months Ended 120 Months Ended
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
MSCI® World Index (reflects no deduction for fees, expenses, or taxes)      
Prospectus [Line Items]      
Average Annual Return, Percent 21.09% 12.15% 12.17%
MSCI® ACWI IMI Core Real Estate Index (reflects no deduction for fees, expenses, or taxes)      
Prospectus [Line Items]      
Average Annual Return, Percent 9.86% 2.57% 3.45%
GLOBAL REAL ESTATE INDEX FUND      
Prospectus [Line Items]      
Average Annual Return, Percent 10.42% 2.99% 3.83%
GLOBAL REAL ESTATE INDEX FUND | After Taxes on Distributions      
Prospectus [Line Items]      
Average Annual Return, Percent 8.68% 1.97% 2.67%
GLOBAL REAL ESTATE INDEX FUND | After Taxes on Distributions and Sales      
Prospectus [Line Items]      
Average Annual Return, Percent 6.15% 1.98% 2.52%