Intangible Assets

12 Months Ended

Dec. 31, 2020

Goodwill And Intangible Assets Disclosure [Abstract]

Intangible Assets

7.  Intangible Assets

The carrying amount of goodwill at December 31, 2020 and 2019 allocated by domestic and foreign operations is as follows (in millions):

	Brokerage		Risk Management		Corporate		Total
At December 31, 2020
United States	$	3,399.8	$	33.2	$	-	$	3,433.0
United Kingdom		1,328.3		15.1		-		1,343.4
Canada		492.9		-		-		492.9
Australia		462.1		11.5		-		473.6
New Zealand		221.9		10.7		-		232.6
Other foreign		148.6		-		2.9		151.5
Total goodwill - net	$	6,053.6	$	70.5	$	2.9	$	6,127.0
At December 31, 2019
United States		3,163.8		33.1		-		3,196.9
United Kingdom		1,177.8		12.9		-		1,190.7
Canada		454.4		-		-		454.4
Australia		416.5		10.5		-		427.0
New Zealand		208.0		10.1		-		218.1
Other foreign		128.4		-		3.0		131.4
Total goodwill - net	$	5,548.9	$	66.6	$	3.0	$	5,618.5

The changes in the carrying amount of goodwill for 2020 and 2019 are as follows (in millions):

	Brokerage			Risk Management			Corporate			Total
Balance as of December 31, 2018	$	4,573.6		$	49.3		$	2.7		$	4,625.6
Goodwill acquired during the year		958.4			16.9			0.4			975.7
Goodwill adjustments related to appraisals and other acquisition    adjustments		0.2			(0.2	)		-			-
Goodwill written-off related to sales of business		(7.2	)		-			-			(7.2	)
Foreign currency translation adjustments during the year		23.9			0.6			(0.1	)		24.4
Balance as of December 31, 2019		5,548.9			66.6			3.0			5,618.5
Goodwill acquired during the year		359.6			-			-			359.6
Goodwill adjustments related to appraisals and other acquisition    adjustments		29.8			1.7			-			31.5
Foreign currency translation adjustments during the year		115.3			2.2			(0.1	)		117.4
Balance as of December 31, 2020	$	6,053.6		$	70.5		$	2.9		$	6,127.0

Major classes of amortizable intangible assets consist of the following (in millions):

	December 31,
	2020			2019
Expiration lists	$	4,753.2		$	4,246.0
Accumulated amortization - expiration lists		(2,436.7	)		(2,004.3	)
		2,316.5			2,241.7
Non-compete agreements		75.9			68.4
Accumulated amortization - non-compete agreements		(57.8	)		(52.5	)
		18.1			15.9
Trade names		107.8			91.8
Accumulated amortization - trade names		(42.5	)		(30.7	)
		65.3			61.1
Net amortizable assets	$	2,399.9		$	2,318.7

Estimated aggregate amortization expense for each of the next five years is as follows (in millions):

2021	$	378.4
2022		352.3
2023		327.1
2024		291.3
2025		251.3
Thereafter		799.5
Total	$	2,399.9