Intangible Assets

9 Months Ended

Sep. 30, 2021

6. Intangible Assets

The carrying amount of goodwill at September 30, 2021 and December 31, 2020 allocated by domestic and foreign operations is as follows (in millions):

The changes in the carrying amount of goodwill for the nine-month period ended September 30, 2021 are as follows (in millions):

	Brokerage			Risk Management			Corporate		Total
Balance as of December 31, 2020	$	6,053.6		$	70.5		$	2.9	$	6,127.0
Goodwill acquired during the period		421.9			31.6			—		453.5
Goodwill adjustments due to appraisals and other acquisition adjustments		50.5			—			—		50.5
Goodwill written-off related to sales of business and impairment		(1.0	)		—			—		(1.0	)
Foreign currency translation adjustments during the period		(2.2	)		(0.3	)		—		(2.5	)
Balance as of September 30, 2021	$	6,522.8		$	101.8		$	2.9	$	6,627.5

Major classes of amortizable intangible assets at September 30, 2021 and December 31, 2020 consist of the following (in millions):

	September 30,			December 31,
	2021			2020
Expiration lists	$	4,997.2		$	4,753.2
Accumulated amortization - expiration lists		(2,727.5	)		(2,436.7	)
		2,269.7			2,316.5
Non-compete agreements		73.5			75.9
Accumulated amortization - non-compete agreements		(61.9	)		(57.8	)
		11.6			18.1
Trade names		105.5			107.8
Accumulated amortization - trade names		(47.8	)		(42.5	)
		57.7			65.3
Net amortizable assets	$	2,339.0		$	2,399.9

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