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Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount before accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Goodwill and Identifiable Assets (Goodwill) (Details) - USD ($) $ in Millions		6 Months Ended	12 Months Ended
	Jan. 24, 2020	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Roll Forward]
Gross goodwill		$ 1,547.3	$ 1,486.9	$ 1,421.1
Translation adjustment		(0.7)	(0.3)
Apex
Goodwill [Roll Forward]
Gross goodwill		703.0	703.5	662.1
Translation adjustment		(0.5)
Oxford
Goodwill [Roll Forward]
Gross goodwill		230.3	230.5	230.8
Translation adjustment		(0.2)	(0.3)
ECS
Goodwill [Roll Forward]
Gross goodwill		614.0	552.9	$ 528.2
DHA
Goodwill [Roll Forward]
Goodwill, Acquired During Period			24.7
Intersys
Goodwill [Roll Forward]
Goodwill, Acquired During Period			$ 41.4
BlackStone Federal
Goodwill [Roll Forward]
Goodwill, Acquired During Period	$ 61.1	$ 61.1