Investment Securities (Details 2) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended
Jun. 22, 2012	May 26, 2012	Feb. 25, 2012
Investment securities disclosures
Long term - available-for-sale securities: Auction rate securities		$ 72.2	$ 73.7
Short term: Held-to-maturity securities		609.3	749.9
Long term - trading securities: Nonqualified deferred compensation plan assets		22.5	22.1
Auction Rate Securities
Investment securities disclosures
Available-for-sale investment securities, at par value		77.4	83.9
Temporary valuation adjustment on available-for-sale investment securities		3.1	3.7
Minimum asset coverage ratio required (as a percent)		200.00%	200.00%
Long term - available-for-sale securities: Auction rate securities		72.2	73.7
Available-for-sale securities redeemed at par	2.1	6.5
U. S. Treasury Securities
Investment securities disclosures
Short term: Held-to-maturity securities		609.3	749.9
Long Term Trading Investment Securities
Investment securities disclosures
Long term - trading securities: Nonqualified deferred compensation plan assets		$ 22.5	$ 22.1

Equity securities categorized neither as held-to-maturity nor trading which are intended be sold more than one year from the balance sheet date or operating cycle, if longer.

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-Name Emerging Issues Task Force (EITF)

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+ Details

- Definition

This item represents investments in debt securities which are categorized as held-to-maturity and that have scheduled maturities within one year of the balance sheet date or the normal operating cycle, whichever is longer; such investments are measured at amortized cost (carrying value). The held-to-maturity category is for those securities that the Entity has the positive intent and ability to hold until maturity.

+ References

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

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

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+ Details