Intangible Assets

12 Months Ended

Dec. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible Assets

7. Intangible Assets

The carrying amount of goodwill at December 31, 2018 and 2017 allocated by domestic and foreign operations is as follows (in millions):

			Risk
	Brokerage		Management		Corporate		Total
At December 31, 2018
United States	$	2,715.3	$	29.6	$	—	$	2,744.9
United Kingdom		753.7		9.2		—		762.9
Canada		378.6		—		—		378.6
Australia		406.3		0.3		—		406.6
New Zealand		209.6		10.2		—		219.8
Other foreign		110.1		—		2.7		112.8
Total goodwill - net	$	4,573.6	$	49.3	$	2.7	$	4,625.6
At December 31, 2017
United States	$	2,280.9	$	25.8	$	—	$	2,306.7
United Kingdom		738.5		7.2		—		745.7
Canada		374.0		—		—		374.0
Australia		416.6		—		—		416.6
New Zealand		209.3		9.6		—		218.9
Other foreign		99.9		—		3.0		102.9
Total goodwill - net	$	4,119.2	$	42.6	$	3.0	$	4,164.8

The changes in the carrying amount of goodwill for 2018 and 2017 are as follows (in millions):

				Risk
	Brokerage			Management			Corporate			Total
Balance as of January 1, 2017, as reported	$	3,736.9		$	28.1		$	2.8		$	3,767.8
Adoption of Topic 606 related to 2016 acquisitions		(14.6	)		—			—			(14.6	)
Balance as of January 1, 2017, as restated		3,722.3			28.1			2.8			3,753.2
Goodwill acquired during the year		290.4			14.1			—			304.5
Adoption of Topic 606 related to 2017 acquisitions		(18.5	)		—			—			(18.5	)
Goodwill adjustments related to appraisals and other acquisition adjustments		14.7			—			—			14.7
Foreign currency translation adjustments during the year		110.3			0.4			0.2			110.9
Balance as of December 31, 2017, as restated		4,119.2			42.6			3.0			4,164.8
Goodwill acquired during the year		574.7			9.9			—			584.6
Goodwill adjustments related to appraisals and other acquisition adjustments		2.2			(2.3	)		—			(0.1	)
Foreign currency translation adjustments during the year		(122.5	)		(0.9	)		(0.3	)		(123.7	)
Balance as of December 31, 2018	$	4,573.6		$	49.3		$	2.7		$	4,625.6

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

	December 31,
	2018			2017
Expiration lists	$	3,379.4		$	3,055.9
Accumulated amortization - expiration lists		(1,676.8	)		(1,422.1	)
		1,702.6			1,633.8
Non-compete agreements		58.0			53.5
Accumulated amortization - non-compete agreements		(48.5	)		(46.1	)
		9.5			7.4
Trade names		86.0			25.9
Accumulated amortization - trade names		(25.1	)		(22.5	)
		60.9			3.4
Net amortizable assets	$	1,773.0		$	1,644.6

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

2019	$	287.2
2020		270.7
2021		247.3
2022		222.2
2023		198.2
Thereafter		547.4
Total	$	1,773.0