Commitments and Contingencies (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) Years	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Operating Leases, Rent Expense	$ 18.4	$ 10.7	$ 9.6
Letters of Credit Outstanding, Amount	$ 8.2
Long-term Purchase Commitments, Range of Years, Minimum | Years	1
Long-Term Purchase Commitments, Range of Years, Maximum | Years	3
Long-term Purchase Commitment, Amount	$ 157.0	205.0
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019	10.9
2020	9.4
2021	6.1
2022	4.5
2023	3.9
Thereafter	23.7
Total	58.5
Asset Retirement Obligation [Abstract]
Balance, beginning of period	2.3	1.8
Hawaiian Telcom opening balance sheet adjustment	6.6	0.0
Liabilities Incurred	0.0	0.4
Liabilities settled	(0.1)	0.0
Accretion expense	0.3	0.1
Balance, end of period	$ 9.1	$ 2.3	$ 1.8