S000012717 [Member] Expense Example - GLOBAL REAL ESTATE INDEX FUND - GLOBAL REAL ESTATE INDEX FUND	Mar. 31, 2026 USD ($)
Prospectus [Line Items]
Expense Example, with Redemption, 1 Year	$ 52
Expense Example, with Redemption, 3 Years	170
Expense Example, with Redemption, 5 Years	299
Expense Example, with Redemption, 10 Years	$ 674

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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