Quarterly Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Revenues from services	$ 20,724.4	$ 18,001.0	$ 20,863.5
Gross profit	3,407.5	2,824.7	3,375.1
Operating profit (loss)	585.4	187.6	644.9
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 382.4	$ 23.8	$ 465.7
Net earnings (loss) per share - basic	$ 7.01	$ 0.41	$ 7.78
Net earnings (loss) per share - diluted	6.91	0.41	7.72
Dividends per share (in dollars per share)	$ 2.52	$ 2.26	$ 2.18