Fair Value Measurements (Fair Value Inputs) (Details) - Significant Unobservable Inputs (Level 3) [Member] - Auction-rate securities [Member] - Fair Value Measurements, Recurring [Member]	9 Months Ended
Oct. 29, 2016
Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Durations until redemption (years)	7 years 2 months 12 days
Discount rates (percent)	3.67%
Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Durations until redemption (years)	8 years 6 months
Discount rates (percent)	3.67%
Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Durations until redemption (years)	7 years 9 months 18 days
Discount rates (percent)	3.67%

Period the instrument, asset or liability is expected to be outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

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