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Stockholders' Equity (Details) (USD $)
In Millions, except Share data, unless otherwise specified |
12 Months Ended | 12 Months Ended | 1 Months Ended | 12 Months Ended | 1 Months Ended | 2 Months Ended | 12 Months Ended | 13 Months Ended | ||||||||||||||
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Feb. 29, 2012
ClassesofCommonStock
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Feb. 28, 2011
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Jul. 31, 2009
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Feb. 29, 2012
Class B Convertible Common Stock [Member]
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Feb. 28, 2011
Class B Convertible Common Stock [Member]
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Apr. 30, 2012
Common Class A and Class B [Member]
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Apr. 30, 2011
Common Class A and Class B [Member]
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Apr. 30, 2010
Common Class A and Class B [Member]
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Feb. 29, 2012
Class 1 Common Stock [Member]
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Feb. 28, 2011
Class 1 Common Stock [Member]
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Jul. 31, 2009
Class 1 Common Stock [Member]
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Jun. 30, 2009
Class 1 Common Stock [Member]
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Apr. 30, 2012
Class A Common Stock [Member]
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Nov. 30, 2010
Class A Common Stock [Member]
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May 31, 2010
Class A Common Stock [Member]
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Apr. 30, 2010
Class A Common Stock [Member]
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Apr. 30, 2012
Class A Common Stock [Member]
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Feb. 29, 2012
Class A Common Stock [Member]
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Feb. 28, 2011
Class A Common Stock [Member]
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Apr. 30, 2012
Class A Common Stock [Member]
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Jul. 31, 2009
Class A Common Stock [Member]
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Jun. 30, 2009
Class A Common Stock [Member]
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| Stockholders' Equity (Textual) | ||||||||||||||||||||||
| Number of classes of common stock with a material number of shares outstanding | 2 | |||||||||||||||||||||
| Common Stock, shares authorized | 378,000,000 | 30,000,000 | 30,000,000 | 25,000,000 | 25,000,000 | 25,000,000 | 15,000,000 | 322,000,000 | 322,000,000 | 322,000,000 | 315,000,000 | |||||||||||
| Common Stock, shares outstanding | 23,578,116 | 11,549 | 170,736,356 | |||||||||||||||||||
| Maximum authorized repurchase of common stock | $ 1,000.0 | $ 500.0 | $ 300.0 | |||||||||||||||||||
| Common stock repurchased, shares | 21,234,266 | 17,240,101 | 6,386,051 | 3,421,924 | 2,785,029 | 11,016,451 | 3,970,481 | 21,234,266 | 17,223,404 | 25,204,747 | ||||||||||||
| Common stock repurchased | $ 413.7 | $ 300.3 | $ 137.1 | $ 86.3 | $ 413.7 | $ 300.0 | $ 500.0 | |||||||||||||||
| Average cost of common stock repurchased | $ 21.47 | $ 21.74 | $ 19.48 | $ 17.42 | $ 19.84 | |||||||||||||||||
| Common Stock, conversion features | Convertible on a one-to-one basis to Class A Common Stock | Convertible on a one-to-one basis to Class A Common Stock | ||||||||||||||||||||
| Common Stock, voting rights | 10 votes per share | Generally nonvoting | 1 vote per share | |||||||||||||||||||
| Common Stock, dividend rights | At least 10 percent greater than Class B Convertible Common Stock and Class 1 Common Stock | |||||||||||||||||||||