Goodwill and Intangible Assets Intangible Assets (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets, Finite-lived	$ 0.0	$ 0.0
Useful Lives	14
Amortization of Intangible Assets	$ 2.5	0.2
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	10.0
Finite-Lived Intangible Assets, Amortization Expense, Year Two	10.0
Finite-Lived Intangible Assets, Amortization Expense, Year Three	10.0
Finite-Lived Intangible Assets, Amortization Expense, Year Four	10.0
Finite-Lived Intangible Assets, Amortization Expense, Year Five	10.0
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	82.3
Finite-Lived Intangible Assets, Amortization Expense, Rolling after Year Five	132.3
IT Services and Hardware [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	141.8	7.0
Accumulated Amortization	(9.5)	(7.0)
Customer relationships | IT Services and Hardware [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	116.0	7.0
Accumulated Amortization	$ (8.9)	(7.0)
Trade name
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	10 years
Trade name | IT Services and Hardware [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 15.9	0.0
Accumulated Amortization	$ (0.4)	0.0
Technology
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	10 years
Technology | IT Services and Hardware [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 9.9	0.0
Accumulated Amortization	$ (0.2)	$ 0.0
Minimum [Member] | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	8 years
Maximum [Member] | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Asset, Useful Life	15 years