Expense Example, No Redemption (Vanguard Federal Money Market Fund Participant)	Vanguard Federal Money Market Fund Vanguard Federal Money Market Fund - Investor Shares 9/1/2013 - 8/31/2014 USD ($)
Expense Example, No Redemption:
1 YEAR	11
3 YEAR	35
5 YEAR	62
10 YEAR	141

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You would pay the following expenses if you did not redeem your shares. Include the second 1-, 3-, 5-, and 10-year periods and related narrative explanation only if a sales charge (load) or other fee is charged upon redemption.

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

-Publisher SEC

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-Number N-1A

-Chapter A

-Section 3

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- Definition

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

-Publisher SEC

-Name Form

-Number N-1A

-Chapter A

-Section 3

-Subsection example

-Paragraph 2

-Subparagraph 1

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Data Type:	rr:NonNegativeMonetaryType
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Period Type:	duration

- Definition

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

-Publisher SEC

-Name Form

-Number N-1A

-Chapter A

-Section 3

-Subsection instructions

-Paragraph 4

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- Definition

+ References

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

-Publisher SEC

-Name Form

-Number N-1A

-Chapter A

-Section 3

-Subsection instructions

-Paragraph 4

-Subparagraph f

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Name:	rr_ExpenseExampleNoRedemptionYear10
Namespace Prefix:	rr_
Data Type:	rr:NonNegativeMonetaryType
Balance Type:	na
Period Type:	duration