Goodwill and Intangible Assets - Other Intangibles (Details) - USD ($) $ in Millions	3 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022
Finite-lived Intangible Assets [Roll Forward]
Amortization	$ (103.7)	$ (103.9)	$ (106.7)	$ (111.1)	$ (112.0)	$ (115.8)
Other indefinite-lived intangibles
Balance at beginning of period	1,280.0	1,280.0	1,280.0	1,280.0	1,280.0	1,280.0
Additions at cost	0.0	0.0	0.0	0.0	0.0	0.0
Other	0.0	0.0	0.0	0.0	0.0	0.0
Balance at end of period	1,280.0	1,280.0	1,280.0	1,280.0	1,280.0	1,280.0
Total
Balance at beginning of period	4,113.3	4,218.6	4,320.1	4,541.7	4,689.7	4,824.5
Additions at cost	0.1	0.1	0.1	0.2	0.2	0.2
Amortization	(103.7)	(103.9)	(106.7)	(111.1)	(112.0)	(115.8)
Other	(11.3)	(1.5)	5.1	(34.9)	(36.2)	(19.2)
Balance at end of period	3,998.4	4,113.3	4,218.6	4,395.9	4,541.7	4,689.7
Customer relationships
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period	1,424.4	1,481.0	1,536.7	1,657.4	1,726.7	1,793.3
Additions at cost	0.0	0.0	0.0	0.0	0.0	0.0
Amortization	(55.0)	(55.1)	(56.8)	(59.4)	(59.7)	(61.9)
Other	(1.9)	(1.5)	1.1	(8.5)	(9.6)	(4.7)
Balance at end of period	1,367.5	1,424.4	1,481.0	1,589.5	1,657.4	1,726.7
Total
Amortization	(55.0)	(55.1)	(56.8)	(59.4)	(59.7)	(61.9)
Reacquired rights
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period	238.8	243.6	245.5	251.3	271.7	284.7
Additions at cost	0.0	0.0	0.0	0.0	0.0	0.0
Amortization	(4.7)	(4.8)	(4.7)	(4.5)	(4.7)	(5.1)
Other	(6.6)	0.0	2.8	(16.6)	(15.7)	(7.9)
Balance at end of period	227.5	238.8	243.6	230.2	251.3	271.7
Total
Amortization	(4.7)	(4.8)	(4.7)	(4.5)	(4.7)	(5.1)
Database
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period	1,017.6	1,059.1	1,100.0	1,186.8	1,235.9	1,285.1
Additions at cost	0.0	0.0	0.0	0.0	0.0	0.0
Amortization	(39.7)	(39.8)	(41.0)	(43.0)	(43.2)	(44.6)
Other	(0.7)	(1.7)	0.1	(4.9)	(5.9)	(4.6)
Balance at end of period	977.2	1,017.6	1,059.1	1,138.9	1,186.8	1,235.9
Total
Amortization	(39.7)	(39.8)	(41.0)	(43.0)	(43.2)	(44.6)
Other intangibles
Finite-lived Intangible Assets [Roll Forward]
Balance at beginning of period	152.5	154.9	157.9	166.2	175.4	181.4
Additions at cost	0.1	0.1	0.1	0.2	0.2	0.2
Amortization	(4.3)	(4.2)	(4.2)	(4.2)	(4.4)	(4.2)
Other	(2.1)	1.7	1.1	(4.9)	(5.0)	(2.0)
Balance at end of period	146.2	152.5	154.9	157.3	166.2	175.4
Total
Amortization	$ (4.3)	$ (4.2)	$ (4.2)	$ (4.2)	$ (4.4)	$ (4.2)