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Quarterly Financial Data (Unaudited) (Details) (USD $)
In Millions, except Per Share data, unless otherwise specified |
3 Months Ended | 12 Months Ended | |||||||||
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May 31, 2012
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Feb. 29, 2012
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Nov. 30, 2011
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Aug. 31, 2011
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May 31, 2011
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Feb. 28, 2011
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Nov. 30, 2010
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Aug. 31, 2010
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May 31, 2012
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May 31, 2011
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May 31, 2010
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| Selected Quarterly Financial Information [Abstract] | |||||||||||
| Service revenue | $ 540.7 | $ 558.5 | $ 535.0 | $ 552.0 | $ 510.4 | $ 519.6 | $ 500.0 | $ 506.2 | $ 2,186.2 | $ 2,036.2 | $ 1,945.8 |
| Interest on funds held for clients | 10.8 | 11.0 | 10.7 | 11.1 | 12.3 | 11.7 | 12.0 | 12.1 | 43.6 | 48.1 | 55.0 |
| Total revenue | 551.5 | 569.5 | 545.7 | 563.1 | 522.7 | 531.3 | 512.0 | 518.3 | 2,229.8 | 2,084.3 | 2,000.8 |
| Operating income | 195.9 | 210.4 | 217.9 | 229.7 | 182.8 | 198.9 | 203.9 | 200.8 | 853.9 | 786.4 | 724.8 |
| Investment income, net | 1.8 | 1.6 | 1.5 | 1.5 | 1.4 | 1.5 | 1.5 | 1.4 | 6.4 | 5.8 | 4.5 |
| Income before income taxes | 197.7 | 212.0 | 219.4 | 231.2 | 184.2 | 200.4 | 205.4 | 202.2 | 860.3 | 792.2 | 729.3 |
| Income taxes | 74.4 | 76.6 | 79.0 | 82.3 | 65.3 | 69.8 | 71.5 | 70.3 | 312.3 | 276.9 | 252.3 |
| Net income | 123.3 | 135.4 | 140.4 | 148.9 | 118.9 | 130.6 | 133.9 | 131.9 | 548.0 | 515.3 | 477.0 |
| Basic earnings per share | $ 0.34 | $ 0.37 | $ 0.39 | $ 0.41 | $ 0.33 | $ 0.36 | $ 0.37 | $ 0.36 | $ 1.51 | $ 1.42 | $ 1.32 |
| Diluted earnings per share | $ 0.34 | $ 0.37 | $ 0.39 | $ 0.41 | $ 0.33 | $ 0.36 | $ 0.37 | $ 0.36 | $ 1.51 | $ 1.42 | $ 1.32 |
| Weighted-average common shares outstanding | 362.6 | 362.5 | 362.4 | 362.2 | 362.0 | 361.8 | 361.7 | 361.6 | 362.4 | 361.8 | 361.4 |
| Weighted-average common shares outstanding, assuming dilution | 363.4 | 363.1 | 362.8 | 362.8 | 363.0 | 362.6 | 362.1 | 362.0 | 363.0 | 362.4 | 361.7 |
| Cash dividends per common share | $ 0.32 | $ 0.32 | $ 0.32 | $ 0.31 | $ 0.31 | $ 0.31 | $ 0.31 | $ 0.31 | $ 1.27 | $ 1.24 | $ 1.24 |
| Total net realized gains | $ 0.4 | $ 0.4 | $ 0.1 | $ 0.1 | $ 0.9 | $ 0.1 | $ 0.2 | $ 0.1 | $ 1.0 | $ 1.3 | $ 3.2 |
| X | ||||||||||
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- Definition
Aggregate dividends paid during the period for each share of common stock outstanding. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The net realized gain (loss) on investments sold during the period, not including gains (losses) on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity, which, for cash flow reporting, is a component of proceeds from investing activities. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Interest generated from day to day operating activities of the business. This element represents a revenue generating activity and is therefore gross (before any related cost of revenue items). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The aggregate amount of income from investments (for example, dividends) not considered a component of the entity's core operations. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The portion of profit or loss for the period, net of income taxes, which is attributable to the parent. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The net result for the period of deducting operating expenses from operating revenues. No definition available.
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- Definition
Aggregate revenue recognized during the period (derived from goods sold, services rendered, insurance premiums, or other activities that constitute an entity's earning process). For financial services companies, also includes investment and interest income, and sales and trading gains. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Aggregate revenue during the period from services rendered in the normal course of business, after deducting allowances and discounts. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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- Definition
The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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