Consolidated Statements of Operations (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Revenues from services	$ 5,044.9	$ 5,522.4
Cost of services	4,240.1	4,637.0
Gross profit	804.8	885.4
Selling and administrative expenses	699.3	731.6
Operating profit	105.5	153.8
Interest and other expenses	11.9	16.1
Earnings before income taxes	93.6	137.7
Provision for income taxes	40.1	40.7
Net earnings	$ 53.5	$ 97.0
Net earnings per share - basic (in dollars per share)	$ 0.88	$ 1.46
Net earnings per share - diluted (in dollars per share)	$ 0.88	$ 1.45
Weighted average shares - basic (in shares)	60.6	66.3
Weighted average shares - diluted (in shares)	61.0	66.9