Intangible Assets (Tables)

6 Months Ended

Jun. 30, 2021

The carrying amount of goodwill at June 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 six-month period ended June 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		355.2			32.0		—		387.2
Goodwill adjustments due to appraisals and other acquisition adjustments		52.5			—		—		52.5
Goodwill written-off related to sales of business and impairment		(1.0	)		—		—		(1.0	)
Foreign currency translation adjustments during the period		64.2			0.4		—		64.6
Balance as of June 30, 2021	$	6,524.5		$	102.9	$	2.9	$	6,630.3

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

	June 30,			December 31,
	2021			2020
Expiration lists	$	5,017.9		$	4,753.2
Accumulated amortization - expiration lists		(2,655.0	)		(2,436.7	)
		2,362.9			2,316.5
Non-compete agreements		88.6			75.9
Accumulated amortization - non-compete agreements		(62.9	)		(57.8	)
		25.7			18.1
Trade names		105.7			107.8
Accumulated amortization - trade names		(47.0	)		(42.5	)
		58.7			65.3
Net amortizable assets	$	2,447.3		$	2,399.9

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