Acquisitions (Narrative) (Details) $ in Millions	2 Months Ended	3 Months Ended	12 Months Ended
	Feb. 24, 2020 USD ($) item	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($) item entity	Dec. 31, 2018 USD ($) item	Dec. 31, 2017 USD ($) item
Business Acquisition [Line Items]
Number of towers acquired | item			2,443	1,316	1,425
Acquisition costs paid through the issuance of common stock			$ 1.7		$ 63.3
Other Acquisitions [Member]
Business Acquisition [Line Items]
Number of towers acquired | item			2,443	1,316	1,425
Property and equipment			$ 90.8	$ 134.5	$ 114.7
Intangible assets			715.5	280.7	345.3
Other net liabilities assumed			$ 32.8	$ 8.5	$ 3.8
Business Combination [Member]
Business Acquisition [Line Items]
Number of businesses acquired | entity			1
Consideration transferred		$ 3.0
Acquisition costs paid through the issuance of common stock		$ 1.7
Subsequent Event [Member]
Business Acquisition [Line Items]
Number of towers acquired | item	65
Cash paid for acquisition	$ 76.3