Acquisitions (Narrative) (Details) $ in Millions	1 Months Ended	9 Months Ended
	Nov. 05, 2021 USD ($) item	Sep. 30, 2021 USD ($) item	Dec. 31, 2020 USD ($)
Business Acquisition [Line Items]
Performance targets, maximum potential obligation		$ 14.8	$ 35.0
Other Acquisitions [Member]
Business Acquisition [Line Items]
Number of towers acquired | item		222
Property and equipment		$ 15.2
Intangible assets		111.0
Other net assets and liabilities assumed		$ 13.9
Subsequent Event [Member] | Airtel Tanzania [Member]
Business Acquisition [Line Items]
Cash paid for acquisition	$ 231.0
Number of communication sites acquired | item	1,700
Subsequent Event [Member] | Airtel Tanzania [Member] | Previously Announced [Member]
Business Acquisition [Line Items]
Cash paid for acquisition	$ 175.0
Number of communication sites acquired | item	1,400