|
Fair Value Measurements (Details) (USD $)
In Millions, unless otherwise specified |
Aug. 31, 2014
|
May 31, 2014
|
||||
|---|---|---|---|---|---|---|
| Available-for-sale securities: | ||||||
| Available-for-sale securities | $ 2,767.1 | $ 3,391.4 | ||||
|
Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 0.2 | 65.8 | ||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 2,767.1 | 3,391.4 | ||||
| Other | 13.8 | 12.3 | ||||
| Liabilities: | ||||||
| Other long-term liabilities | 13.8 | 12.3 | ||||
|
Quoted prices in active markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 0.2 | 0 | ||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 0 | 0 | ||||
| Other | 13.8 | 12.3 | ||||
| Liabilities: | ||||||
| Other long-term liabilities | 13.8 | 12.3 | ||||
|
Significant other observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 0 | 65.8 | ||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 2,767.1 | 3,391.4 | ||||
| Other | 0 | 0 | ||||
| Liabilities: | ||||||
| Other long-term liabilities | 0 | 0 | ||||
|
Significant unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 0 | 0 | ||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 0 | 0 | ||||
| Other | 0 | 0 | ||||
| Liabilities: | ||||||
| Other long-term liabilities | 0 | 0 | ||||
|
Commercial paper [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 6.0 | |||||
|
Commercial paper [Member] | Quoted prices in active markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 0 | |||||
|
Commercial paper [Member] | Significant other observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 6.0 | |||||
|
Commercial paper [Member] | Significant unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 0 | |||||
|
General obligation municipal bonds [Member]
|
||||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 1,664.5 | 1,628.5 | ||||
|
General obligation municipal bonds [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 10.9 | |||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 1,664.5 | 1,628.5 | ||||
|
General obligation municipal bonds [Member] | Quoted prices in active markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 0 | |||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 0 | 0 | ||||
|
General obligation municipal bonds [Member] | Significant other observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 10.9 | |||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 1,664.5 | 1,628.5 | ||||
|
General obligation municipal bonds [Member] | Significant unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 0 | |||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 0 | 0 | ||||
|
Pre-refunded municipal bonds [Member]
|
||||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 124.2 | [1] | 142.8 | [1] | ||
|
Pre-refunded municipal bonds [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 31.2 | |||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 124.2 | 142.8 | ||||
|
Pre-refunded municipal bonds [Member] | Quoted prices in active markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 0 | |||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 0 | 0 | ||||
|
Pre-refunded municipal bonds [Member] | Significant other observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 31.2 | |||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 124.2 | 142.8 | ||||
|
Pre-refunded municipal bonds [Member] | Significant unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 0 | |||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 0 | 0 | ||||
|
Revenue municipal bonds [Member]
|
||||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 932.7 | 867.8 | ||||
|
Revenue municipal bonds [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 17.7 | |||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 932.7 | 867.8 | ||||
|
Revenue municipal bonds [Member] | Quoted prices in active markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 0 | |||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 0 | 0 | ||||
|
Revenue municipal bonds [Member] | Significant other observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 17.7 | |||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 932.7 | 867.8 | ||||
|
Revenue municipal bonds [Member] | Significant unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 0 | |||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 0 | 0 | ||||
|
Money market securities [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 0.2 | |||||
|
Money market securities [Member] | Quoted prices in active markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 0.2 | |||||
|
Money market securities [Member] | Significant other observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 0 | |||||
|
Money market securities [Member] | Significant unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Assets: | ||||||
| Cash Equivalents | 0 | |||||
|
Variable rate demand notes [Member]
|
||||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 45.7 | 752.3 | ||||
|
Variable rate demand notes [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 45.7 | 752.3 | ||||
|
Variable rate demand notes [Member] | Quoted prices in active markets (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 0 | 0 | ||||
|
Variable rate demand notes [Member] | Significant other observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | 45.7 | 752.3 | ||||
|
Variable rate demand notes [Member] | Significant unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]
|
||||||
| Available-for-sale securities: | ||||||
| Available-for-sale securities | $ 0 | $ 0 | ||||
|
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