CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Income Statement [Abstract]
Consolidated revenue	$ 499.9	$ 517.4
Consolidated expenses:
Compensation and related expenses	240.4	222.3
Selling, general and administrative	91.7	97.1
Intangible amortization and impairments	7.3	12.5
Interest expense	29.9	30.5
Depreciation and other amortization	3.0	3.7
Other expenses (net)	9.0	14.4
Total consolidated expenses	381.3	380.5
Equity method income (net)	117.5	58.6
Investment and other income	18.0	38.0
Income before income taxes	254.1	233.5
Income tax expense	55.4	45.0
Net income	198.7	188.5
Net income (non-controlling interests)	(48.9)	(54.0)
Net income (controlling interest)	$ 149.8	$ 134.5
Average shares outstanding (basic) (in shares)	32.8	35.9
Average shares outstanding (diluted) (in shares)	40.1	39.9
Earnings per share (basic) (in dollars per share)	$ 4.56	$ 3.74
Earnings per share (diluted) (in dollars per share)	$ 4.14	$ 3.47