Fair Value Measurements - Unrealized Gain (Loss) on Investments (Details) (USD $) In Millions, unless otherwise specified	Nov. 29, 2014	May 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cost	$ 6.6	$ 11.1
Unrealized Gain	0	0
Unrealized Loss	0	0
Market Value	6.6	11.1
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cost	0.3	0.4
Unrealized Gain	0	0
Unrealized Loss	0	0
Market Value	0.3	0.4
Corporate Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cost	0.8	1.2
Unrealized Gain	0	0
Unrealized Loss	0	0
Market Value	0.8	1.2
US Treasury and Government
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cost	4.9	7.9
Unrealized Gain	0	0
Unrealized Loss	0	0
Market Value	4.9	7.9
Collateralized Mortgage Backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Cost	0.6	1.6
Unrealized Gain	0	0
Unrealized Loss	0	0
Market Value	$ 0.6	$ 1.6

This item represents the gross unrealized gains of debt and equity securities, derivatives, and long-term debt.

No definition available.

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- Definition

This item represents the gross unrealized losses of debt and equity securities, derivatives, and long-term debt.

+ References

No definition available.

+ Details

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- Definition

This item represents the cost of debt securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.2)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (aa)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

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- Definition

Amount of investments in debt securities classified as available-for-sale, expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=28360136&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26626-111562

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