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Fair Value Measurements (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014
Fair Value Measurements [Abstract]
Convertible Noteholders, New Notes	$ 200

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- Definition

Convertible Noteholders, New Notes

+ References

No definition available.

+ Details

Name:	usu_ConvertibleNoteholdersNewNotes
Namespace Prefix:	usu_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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- Details

Name:	usu_FairValueMeasurementsAbstract
Namespace Prefix:	usu_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration