Investments (Details Textual)	3 Months Ended
May 04, 2012
Schedule of Available-for-sale Securities
Debt securities contractual maturity period	three years or less

The latest date, in a range of maturity dates, that a debt security categorized as neither trading nor held-to-maturity is scheduled to be repaid.

No definition available.

Name:	us-gaap_AvailableforsaleSecuritiesDebtMaturityDateRangeHigh
Namespace Prefix:	us-gaap_
Data Type:	us-types:durationStringItemType
Balance Type:	na
Period Type:	duration