Consolidated Statement of Earnings - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenues before reimbursements	$ 2,453.6	$ 2,012.0	$ 7,533.4	$ 6,424.9
Reimbursements	38.4	32.0	106.6	97.4
Total revenues	2,492.0	2,044.0	7,640.0	6,522.3
Compensation	1,424.5	1,181.8	4,253.0	3,624.9
Operating	423.0	321.5	1,239.1	962.7
Reimbursements	38.4	32.0	106.6	97.4
Cost of revenues from clean coal activities				22.9
Interest	72.8	64.4	218.5	192.9
Depreciation	43.0	32.9	121.5	108.1
Amortization	128.7	112.6	385.3	337.5
Change in estimated acquisition earnout payables	(2.5)	(16.2)	48.7	(29.1)
Total expenses	2,127.9	1,729.0	6,372.7	5,317.3
Earnings before income taxes	364.1	315.0	1,267.3	1,205.0
Provision for income taxes	80.9	58.7	261.7	224.5
Net earnings	283.2	256.3	1,005.6	980.5
Net earnings attributable to noncontrolling interests	2.5	0.5	3.9	1.8
Net earnings attributable to controlling interests	$ 280.7	$ 255.8	$ 1,001.7	$ 978.7
Basic net earnings per share	$ 1.3	$ 1.21	$ 4.67	$ 4.66
Diluted net earnings per share	1.28	1.19	4.58	4.57
Dividends declared per common share	$ 0.55	$ 0.51	$ 1.65	$ 1.53
Commissions [Member]
Revenues before reimbursements	$ 1,381.2	$ 1,186.9	$ 4,539.0	$ 4,034.6
Broker Fees [Member]
Revenues before reimbursements	846.1	671.3	2,342.3	1,913.1
Supplemental Revenue [Member]
Revenues before reimbursements	70.8	64.7	223.6	204.7
Contingent Revenue [Member]
Revenues before reimbursements	53.9	52.4	179.9	167.1
Investment Income [Member]
Revenues before reimbursements	100.6	37.7	242.2	79.1
Net Gains (Losses) on Divestitures [Member]
Revenues before reimbursements	0.5	(1.3)	5.9	2.9
Clean Coal Activities [Member]
Revenues before reimbursements				23.0
Other Net Revenue [Member]
Revenues before reimbursements	$ 0.5	$ 0.3	$ 0.5	$ 0.4