Commitments and Contingencies Other Installment Financing Arrangements (Details) $ in Millions	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Other Installment Financing Arrangements [Line Items]
Financing Arrangement Liability	$ 44.6	$ 0.0
Other Assets, Current	39.2	$ 37.2
2019	0.8
2020	0.8
2021	3.5
2022	5.8
2023	5.8
Thereafter	58.8
Total minimum financing obligations payments	$ 75.5
Joint Pole Asset [Member]
Other Installment Financing Arrangements [Line Items]
Contract Term, in Years	10
Financing Arrangement Liability	$ 40.1
Usage Life, in Years	20
Other Assets, Current	$ 1.0
Data Centers [Member]
Other Installment Financing Arrangements [Line Items]
Contract Term, in Years	10
Financing Arrangement Liability	$ 4.5