Consolidated Statement of Earnings - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues before reimbursements	$ 6,851.9	$ 7,056.4	$ 6,792.4
Reimbursements	151.7	138.6	141.6
Total revenues	7,003.6	7,195.0	6,934.0
Compensation	3,466.5	3,339.5	3,026.3
Operating	906.5	1,068.5	903.7
Reimbursements	151.7	138.6	141.6
Cost of revenues from clean coal activities	882.1	1,352.8	1,816.0
Interest	196.4	179.8	138.4
Depreciation	145.1	140.4	127.8
Amortization	417.3	334.0	291.2
Change in estimated acquisition earnout payables	(32.9)	15.3	9.6
Total expenses	6,132.7	6,568.9	6,454.6
Earnings before income taxes	870.9	626.1	479.4
Provision (benefit) for income taxes	12.8	(89.7)	(196.5)
Net earnings	858.1	715.8	675.9
Net earnings attributable to noncontrolling interests	39.3	47.0	42.4
Net earnings attributable to controlling interests	$ 818.8	$ 668.8	$ 633.5
Basic net earnings per share	$ 4.29	$ 3.60	$ 3.47
Diluted net earnings per share	4.20	3.52	3.40
Dividends declared per common share	$ 1.80	$ 1.72	$ 1.64
Commissions [Member]
Revenues before reimbursements	$ 3,591.9	$ 3,320.6	$ 2,920.7
Broker Fees [Member]
Revenues before reimbursements	1,957.9	1,911.1	1,756.3
Supplemental Revenue [Member]
Revenues before reimbursements	221.9	210.5	189.9
Contingent Revenue [Member]
Revenues before reimbursements	147.0	135.6	98.0
Investment income [Member]
Revenues before reimbursements	75.9	86.9	70.1
Net (Losses) Gains on Divestitures [Member]
Revenues before reimbursements	(5.8)	75.3	10.2
Clean Coal Activities [Member]
Revenues before reimbursements	863.5	1,319.3	1,746.3
Other net (losses) revenue [Member]
Revenues before reimbursements	$ (0.4)	$ (2.9)	$ 0.9