Label	Element	Value
Investor Shares | U.S. Treasury Bills [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	85.70%
Investor Shares | U.S. Treasury Notes [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	14.30%