Annual report pursuant to Section 13 and 15(d)

Income Taxes (Components of Provision for Income Taxes) (Details)

v3.10.0.1
Income Taxes (Components of Provision for Income Taxes) (Details) - USD ($)
$ in Millions
 3 Months Ended 12 Months Ended
May 31, 2018
 [1]
Feb. 28, 2018
 [1]
Nov. 30, 2017
 [1]
Aug. 31, 2017
 [1]
May 31, 2017
Feb. 28, 2017
Nov. 30, 2016
Aug. 31, 2016
May 31, 2018
May 31, 2017
May 31, 2016
Income Taxes [Abstract]                      
Federal                 $ 289.1 $ 362.0 $ 336.4
State                 54.1 48.1 50.8
Total current                 343.2 410.1 387.2
Federal                 18.4 15.9 5.5
State                 0.8 1.5 1.6
Total deferred                 19.2 17.4 7.1
Income taxes $ 91.8 $ 34.4 $ 116.9 $ 119.3 $ 105.2 $ 105.3 $ 109.9 $ 107.1 $ 362.4 [1] $ 427.5 $ 394.3
[1] 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 for further details.