Annual report pursuant to Section 13 and 15(d)

Description of Business, Basis of Presentation, and Significant Accounting Policies (Schedule of Recast of Selected Consolidated Statements of Income and Comprehensive Income) (Details)

v3.19.2
Description of Business, Basis of Presentation, and Significant Accounting Policies (Schedule of Recast of Selected Consolidated Statements of Income and Comprehensive Income) (Details) - USD ($)
$ / shares in Units, $ in Millions
 3 Months Ended 12 Months Ended
May 31, 2019
Feb. 28, 2019
Nov. 30, 2018
Aug. 31, 2018
May 31, 2018
 [1]
Feb. 28, 2018
 [1]
Nov. 30, 2017
 [1]
Aug. 31, 2017
 [1]
May 31, 2019
May 31, 2018
May 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                      
Service revenue $ 958.2 $ 1,047.4 $ 840.6 $ 845.7 $ 828.0 $ 918.0 $ 789.0 $ 779.2 $ 3,691.9 $ 3,314.2 [1],[2] $ 3,102.4 [2],[3]
Operating expenses                 1,177.8 1,018.2 [2] 919.4 [2]
Selling, general and administrative expenses                 1,223.4 1,068.0 [2] 979.7 [2]
Total expenses                 2,401.2 2,086.2 [2] 1,899.1 [2]
Operating income 314.5 429.3 307.2 320.3 302.1 369.0 303.1 317.3 1,371.3 1,291.5 [1],[2] 1,253.9 [2]
Income taxes 80.1 101.0 73.5 79.0 86.9 [4] 4.1 [4] 106.0 [4] 109.0 [4] 333.6 306.0 [1],[2],[4] 432.8 [2],[5]
Net income $ 230.4 $ 324.6 $ 235.8 $ 243.6 $ 217.7 $ 367.2 $ 198.8 $ 210.4 $ 1,034.4 $ 994.1 [1],[2],[6] $ 826.3 [2],[3],[6]
Basic earnings per share $ 0.64 [7] $ 0.90 [7] $ 0.66 [7] $ 0.68 [7] $ 0.61 [7] $ 1.02 [7] $ 0.55 [7] $ 0.59 [7] $ 2.88 [7] $ 2.77 [1],[2],[7] $ 2.30 [2],[3]
Diluted earnings per share $ 0.64 [7] $ 0.90 [7] $ 0.65 [7] $ 0.67 [7] $ 0.60 [7] $ 1.01 [7] $ 0.55 [7] $ 0.58 [7] $ 2.86 [7] $ 2.75 [1],[2],[7] 2.28 [2],[3],[8]
Impact diluted earnings per share amount +/- due to rounding                     $ 0.01
As Previously Reported [Member]                      
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                      
Service revenue                   $ 3,317.4 $ 3,100.7
Operating expenses                   1,017.8 919.6
Selling, general and administrative expenses                   1,075.6 992.1
Total expenses                   2,093.4 1,911.7
Operating income                   1,287.5 1,239.6
Income taxes                   362.4 427.5
Net income                   $ 933.7 $ 817.3
Basic earnings per share                   $ 2.60 $ 2.27
Diluted earnings per share                   $ 2.58 $ 2.25 [8]
Adjustments [Member] | ASU 2014-09 [Member]                      
New Accounting Pronouncements or Change in Accounting Principle [Line Items]                      
Service revenue                   $ (3.2) $ 1.7
Operating expenses                   0.4 (0.2)
Selling, general and administrative expenses                   (7.6) (12.4)
Total expenses                   (7.2) (12.6)
Operating income                   4.0 14.3
Income taxes                   (56.4) 5.3
Net income                   $ 60.4 $ 9.0
Basic earnings per share                   $ 0.17 $ 0.03
Diluted earnings per share                   $ 0.17 $ 0.02 [8]
[1] Amounts have been adjusted to reflect the adoption of ASC Topic 606.
[2] Amounts have been adjusted to reflect the adoption of Accounting Standards Codification ("ASC") Topic 606, "Revenue from Contracts with Customers" ("ASC Topic 606").
[3] Amounts have been adjusted to reflect the adoption of ASC Topic 606.
[4] As a result of the Tax Act, the effective income tax rate for the three months ended February 28, 2018 was significantly impacted by certain one-time net tax benefits. Refer to Note K of this Item 8 for further details.
[5] Amounts have been adjusted to reflect the adoption of ASC Topic 606.
[6] Amounts have been adjusted to reflect the adoption of Accounting Standards Update ("ASU") No. 2016-18, "Statement of Cash Flows (Topic 230): Restricted Cash (a consensus of the FASB Emerging Issues Task Force)."
[7] Each quarter is a discrete period and the sum of the four quarters' basic and diluted earnings per share amounts may not equal the full year amount.
[8] Diluted earnings per share amounts may not add across by +/- $0.01 due to rounding.