Segment Information - Summarized Financial Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenues	$ 1,114.0	$ 1,051.6	$ 1,026.0
Operating expenses	625.4	569.5	582.6
Depreciation and amortization	217.0	206.5	208.3
Transition and integration costs	6.6	13.1	2.3
Operating income	265.0	262.5	232.8
Interest expense	(51.7)	(57.5)	(67.6)
Other expense, net	(7.1)	(12.6)	(6.4)
Earnings before income taxes	206.2	192.4	158.8
Income tax expense (benefit)	37.7	(61.8)	25.8
Net earnings from continuing operations	168.5	254.2	133.0
Balance sheet data:
Total assets	3,653.4	3,655.9	3,762.0
Goodwill	2,329.7	2,306.8	2,303.8
Earnings Before Interest, Taxes, Depreciation, and Amortization	482.0	469.0	441.1
Operating Segments | Software Solutions
Segment Reporting Information [Line Items]
Revenues	962.0	904.5	860.7
Operating expenses	394.8	388.0	374.6
Depreciation and amortization	112.9	101.2	107.0
Transition and integration costs	0.0	0.0	0.0
Operating income	454.3	415.3	379.1
Balance sheet data:
Total assets	3,227.8	3,223.5	3,242.0
Goodwill	2,157.6	2,134.7	2,131.7
Earnings Before Interest, Taxes, Depreciation, and Amortization	567.2	516.5	486.1
Operating Segments | Data and Analytics
Segment Reporting Information [Line Items]
Revenues	154.5	151.6	172.6
Operating expenses	115.0	113.2	144.4
Depreciation and amortization	14.1	12.8	8.0
Transition and integration costs	0.0	0.0	0.0
Operating income	25.4	25.6	20.2
Balance sheet data:
Total assets	310.2	304.7	310.3
Goodwill	172.1	172.1	172.1
Earnings Before Interest, Taxes, Depreciation, and Amortization	39.5	38.4	28.2
Corporate and Other
Segment Reporting Information [Line Items]
Revenues	(2.5)	(4.5)	(7.3)
Operating expenses	115.6	68.3	63.6
Depreciation and amortization	90.0	92.5	93.3
Transition and integration costs	6.6	13.1	2.3
Operating income	(214.7)	(178.4)	(166.5)
Balance sheet data:
Total assets	115.4	127.7	209.7
Goodwill	0.0	0.0	0.0
Earnings Before Interest, Taxes, Depreciation, and Amortization	$ (124.7)	$ (85.9)	$ (73.2)