Goodwill and Intangible Assets - Intangible Assets (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets		$ 2.3		$ 4.9
Impairment of Intangible Assets, Finite-lived		0.0	$ 0.0	0.0	$ 0.0
IT Services and Hardware [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	139.1		139.1		$ 141.8
Finite-Lived Intangible Assets, Accumulated Amortization		(14.4)		(14.4)		(9.5)
Finite-Lived Intangible Assets, Net		124.7		124.7		132.3
Customer Relationships [Member] | IT Services and Hardware [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	114.3		114.3		116.0
Finite-Lived Intangible Assets, Accumulated Amortization		(12.6)		(12.6)		(8.9)
Finite-Lived Intangible Assets, Net		101.7		101.7		107.1
Trade Names [Member] | IT Services and Hardware [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	15.0		15.0		15.9
Finite-Lived Intangible Assets, Accumulated Amortization		(1.1)		(1.1)		(0.4)
Finite-Lived Intangible Assets, Net		13.9		13.9		15.5
Technology-Based Intangible Assets [Member] | IT Services and Hardware [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	[1]	9.8		9.8		9.9
Finite-Lived Intangible Assets, Accumulated Amortization		(0.7)		(0.7)		(0.2)
Finite-Lived Intangible Assets, Net		$ 9.1		$ 9.1		$ 9.7

[1] Change in gross carrying amounts is due to foreign currency translation.