CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
CONDENSED CONSOLIDATED STATEMENTS OF INCOME
Revenues	$ 1,114.7	$ 1,340.5	$ 2,304.7	$ 2,677.5
Type of Revenue	us-gaap:ServiceMember	us-gaap:ServiceMember	us-gaap:ServiceMember	us-gaap:ServiceMember
Expenses:
Cost of services	$ 662.2	$ 776.4	$ 1,345.6	$ 1,561.4
Type of Cost of Service	us-gaap:ServiceMember	us-gaap:ServiceMember	us-gaap:ServiceMember	us-gaap:ServiceMember
Selling, general, and administrative	$ 230.7	$ 305.2	$ 504.1	$ 606.0
Total expenses	892.9	1,081.6	1,849.7	2,167.4
Operating income	221.8	258.9	455.0	510.1
Other income/(expense):
Gain on divestitures of businesses (Note 4)		524.6		524.6
Interest income	0.8	1.0	2.4	3.1
Interest expense	(29.3)	(38.6)	(62.2)	(78.3)
Other income/(expense), net	(0.1)	(0.3)	(0.1)	2.2
Total other income/(expense), net	(28.6)	486.7	(59.9)	451.6
Income before income taxes	193.2	745.6	395.1	961.7
Provision for income taxes	31.3	130.8	56.5	173.8
Net income	$ 161.9	$ 614.8	$ 338.6	$ 787.9
Earnings per share:
Basic (USD per share)	$ 0.39	$ 1.43	$ 0.82	$ 1.82
Diluted (USD per share)	$ 0.39	$ 1.42	$ 0.81	$ 1.81
Weighted-average shares outstanding:
Basic (shares)	411.5	430.0	412.9	433.8
Diluted (shares)	413.6	432.3	415.9	436.1