Shareholder Report, Holdings (Details)	May 31, 2025
C000036131 \| U.S. Treasury Inflation-Indexed Notes
Holdings [Line Items]
Percent of Net Asset Value	99.70%
C000036131 \| Sequoia Mortgage Trust
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000036131 \| GS Mortgage-Backed Securities Trust
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000036131 \| Federal National Mortgage Assn.
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000036131 \| Federal Home Loan Mortgage
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000036131 \| Government National Mortgage Assn.
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000036131 \| U.S. Government Agency Obligations (Excluding Mortgage-Backed)
Holdings [Line Items]
Percent of Net Asset Value	99.70%
C000036131 \| Non-U.S. Government Mortgage-Backed Securities
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000036131 \| U.S. Government & Agency Mortgage-Backed Securities
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000036131 \| Other Holdings Grouping
Holdings [Line Items]
Percent of Net Asset Value	0.30%
C000161061 \| U.S. Treasury Inflation-Indexed Notes
Holdings [Line Items]
Percent of Net Asset Value	99.70%
C000161061 \| Sequoia Mortgage Trust
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000161061 \| GS Mortgage-Backed Securities Trust
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000161061 \| Federal National Mortgage Assn.
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000161061 \| Federal Home Loan Mortgage
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000161061 \| Government National Mortgage Assn.
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000161061 \| U.S. Government Agency Obligations (Excluding Mortgage-Backed)
Holdings [Line Items]
Percent of Net Asset Value	99.70%
C000161061 \| Non-U.S. Government Mortgage-Backed Securities
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000161061 \| U.S. Government & Agency Mortgage-Backed Securities
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000161061 \| Other Holdings Grouping
Holdings [Line Items]
Percent of Net Asset Value	0.30%
C000219321 \| U.S. Treasury Inflation-Indexed Notes
Holdings [Line Items]
Percent of Net Asset Value	99.70%
C000219321 \| Sequoia Mortgage Trust
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000219321 \| GS Mortgage-Backed Securities Trust
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000219321 \| Federal National Mortgage Assn.
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000219321 \| Federal Home Loan Mortgage
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000219321 \| Government National Mortgage Assn.
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000219321 \| U.S. Government Agency Obligations (Excluding Mortgage-Backed)
Holdings [Line Items]
Percent of Net Asset Value	99.70%
C000219321 \| Non-U.S. Government Mortgage-Backed Securities
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000219321 \| U.S. Government & Agency Mortgage-Backed Securities
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000219321 \| Other Holdings Grouping
Holdings [Line Items]
Percent of Net Asset Value	0.30%

Shareholder Report, Holdings (Details)

May 31, 2025