Revenues - Topic 606 Cash Flow (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred income taxes, net	$ (7.5)	$ (78.4)	$ 3.2
Net earnings	168.5	254.2	133.0
Depreciation and amortization	217.0	206.5	208.3
Trade and other receivables, including receivables from related parties	44.5	(52.5)	(6.4)
Prepaid expenses and other assets	(41.5)	1.7	(11.2)
Deferred revenues	(44.8)	(48.5)	(51.9)
Deferred contract costs	(6.4)	35.6	26.2
Net cash provided by operating activities	435.5	351.1	325.7
Additions to computer software	(73.1)	(53.3)	(41.9)
Net cash used in investing activities	(144.1)	$ (84.7)	$ (230.2)
ASU 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred income taxes, net	(11.4)
Net earnings	157.4
Depreciation and amortization	215.9
Trade and other receivables, including receivables from related parties	42.7
Prepaid expenses and other assets	(35.2)
Deferred revenues	(40.3)
Deferred contract costs	(1.7)
Net cash provided by operating activities	433.1
Additions to computer software	(70.7)
Net cash used in investing activities	(141.7)
Adjustments for ASC 606 Adoption [Member] | ASU 2014-09
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred income taxes, net	(3.9)
Net earnings	(11.1)
Depreciation and amortization	(1.1)
Trade and other receivables, including receivables from related parties	(1.8)
Prepaid expenses and other assets	6.3
Deferred revenues	4.5
Deferred contract costs	4.7
Net cash provided by operating activities	(2.4)
Additions to computer software	2.4
Net cash used in investing activities	$ 2.4