Acquisitions (Narrative) (Details) $ in Millions	1 Months Ended	9 Months Ended
	Nov. 05, 2020 USD ($) item	Sep. 30, 2020 USD ($) item	Dec. 31, 2019 USD ($)
Business Acquisition [Line Items]
Performance targets, maximum potential obligation		$ 24.9	$ 29.7
Other Acquisitions [Member]
Business Acquisition [Line Items]
Number of towers acquired | item		129
Property and equipment		$ 16.7
Intangible assets		100.3
Other net assets and liabilities assumed		$ 4.4
Subsequent Event [Member]
Business Acquisition [Line Items]
Number of towers acquired | item	54
Cash paid for acquisition	$ 14.6