Shareholder Report, Holdings (Details)	Apr. 30, 2025
C000028811 \| AssetUnited States Treasury Obligations
Holdings [Line Items]
Percent of Total Investments	66.40%
C000028811 \| AssetCommodity Indexed Structured Notes
Holdings [Line Items]
Percent of Total Investments	22.70%
C000028811 \| AssetUnited States Agency Obligations
Holdings [Line Items]
Percent of Total Investments	8.40%
C000028811 \| AssetShort-Term Investments
Holdings [Line Items]
Percent of Total Investments	2.50%
C000028812 \| AssetUnited States Treasury Obligations
Holdings [Line Items]
Percent of Total Investments	66.40%
C000028812 \| AssetCommodity Indexed Structured Notes
Holdings [Line Items]
Percent of Total Investments	22.70%
C000028812 \| AssetUnited States Agency Obligations
Holdings [Line Items]
Percent of Total Investments	8.40%
C000028812 \| AssetShort-Term Investments
Holdings [Line Items]
Percent of Total Investments	2.50%
C000028810 \| AssetUnited States Treasury Obligations
Holdings [Line Items]
Percent of Total Investments	66.40%
C000028810 \| AssetCommodity Indexed Structured Notes
Holdings [Line Items]
Percent of Total Investments	22.70%
C000028810 \| AssetUnited States Agency Obligations
Holdings [Line Items]
Percent of Total Investments	8.40%
C000028810 \| AssetShort-Term Investments
Holdings [Line Items]
Percent of Total Investments	2.50%