Goodwill and Identifiable Assets (Tables)

12 Months Ended

Dec. 31, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Goodwill

The changes in the carrying amount of goodwill for the years ended December 31, 2019 and 2018 are as follows (in millions):

 

	Apex Segment		Oxford Segment			ECS Segment		Total
Balance as of December 31, 2017	$	662.1	$	232.0		$	—	$	894.1
ECS acquisition	—		—			528.2		528.2
Translation adjustment	—		(1.2		)	—		(1.2		)
Balance as of December 31, 2018	662.1		230.8			528.2		1,421.1
DHA acquisition	—		—			24.7		24.7
Intersys acquisition	41.4		—			—		41.4
Translation adjustment	—		(0.3		)	—		(0.3		)
Balance as of December 31, 2019	$	703.5	$	230.5		$	552.9	$	1,486.9

Schedule of Acquired Intangible Assets

Acquired intangible assets consisted of the following (in millions):

		December 31, 2019						December 31, 2018
	Estimated Useful Life	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Subject to amortization:
Customer and contractual relationships	2 - 12.75 years	$	384.9	$	179.9	$	205.0	$	346.9	$	145.4	$	201.5
Contractor relationships	2 - 5 years	71.1		70.6		0.5		71.1		67.1		4.0
Backlog	1 - 2.75 years	25.0		23.9		1.1		23.1		17.7		5.4
Non-compete agreements	2 - 7 years	24.8		13.8		11.0		22.1		9.9		12.2
In-use software	6 years	18.9		18.9		—		18.9		16.0		2.9
Favorable contracts	5 years	—		—		—		1.4		0.9		0.5
		524.7		307.1		217.6		483.5		257.0		226.5
Not subject to amortization:
Trademarks(1)		258.9		—		258.9		262.2		—		262.2
Total		$	783.6	$	307.1	$	476.5	$	745.7	$	257.0	$	488.7

Schedule of Estimated Future Amortization Expense

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

2020	$	44.7
2021	37.8
2022	29.4
2023	25.4
2024	19.1
Thereafter	61.2
	$	217.6