Organization and Basis of Presentation - Discontinued Operations, Cash Flow and Significant Non-Cash Items (Details) - Atlantic and Astound broadband markets - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Discontinued Operations, Held-for-sale or Disposed of by Sale
Specified items of cash flow
Capital expenditures	$ 45.4
Non-cash operating activities
Operating lease additions	$ 0.7
Discontinued Operations, Held-for-sale
Specified items of cash flow
Capital expenditures		$ 62.7	$ 103.2
Non-cash operating activities
Operating lease additions		0.7
Non-cash financing activities:
Capital expenditure accounts payable and accruals		$ 2.1	$ 1.0