Intangible Assets

3 Months Ended

Mar. 31, 2021

6. Intangible Assets

The carrying amount of goodwill at March 31, 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 three-month period ended March 31, 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		269.5			19.0		—		288.5
Goodwill adjustments due to appraisals and other acquisition adjustments		52.1			—		—		52.1
Goodwill written-off related to sales of business and impairment		(1.0	)		—		—		(1.0	)
Foreign currency translation adjustments during the period		43.9			0.4		—		44.3
Balance as of March 31, 2021	$	6,418.1		$	89.9	$	2.9	$	6,510.9

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

	March 31,			December 31,
	2021			2020
Expiration lists	$	4,937.9		$	4,753.2
Accumulated amortization - expiration lists		(2,546.9	)		(2,436.7	)
		2,391.0			2,316.5
Non-compete agreements		88.1			75.9
Accumulated amortization - non-compete agreements		(60.0	)		(57.8	)
		28.1			18.1
Trade names		104.4			107.8
Accumulated amortization - trade names		(44.7	)		(42.5	)
		59.7			65.3
Net amortizable assets	$	2,478.8		$	2,399.9

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