Commitments and Contingencies (Details) - USD ($) $ in Millions		9 Months Ended	12 Months Ended
	Apr. 27, 2018	Sep. 30, 2019	Dec. 31, 2019
Commitments and Contingencies
Estimated reimbursement amount		$ 3.1
Telecommunications Capacity
Commitments and Contingencies
Open commitments		73.8
Telecommunications Capacity | Forecast
Commitments and Contingencies
Open commitments met			$ 3.3
Construction Contracts
Commitments and Contingencies
Open commitments		$ 216.3
Pending Litigation
Commitments and Contingencies
Sought amount	$ 21.0
Pending Litigation | Damages Related To Construction Project
Commitments and Contingencies
Sought amount	$ 2.8