Summary Of Significant Accounting Policies (Narrative) (Details) $ in Thousands	1 Months Ended		12 Months Ended
	Dec. 31, 2017 USD ($) item	Nov. 30, 2014 USD ($) item	Dec. 31, 2017 USD ($) item entity	Dec. 31, 2016 USD ($) item	Dec. 31, 2015 USD ($) item
Summary of Significant Accounting Policies [Line Items]
Proceeds from sale of other investments			$ 200	$ 700
Gain on sale of investments			0	0	$ 38,326
Cost-method investments, carrying value	$ 8,600		8,600	8,100
Cost-method investments, impairment loss			0	0	0
Interest cost capitalized			1,100	1,000	800
Deferred lease costs	11,000		11,000	10,200	10,900
Amortization expense	13,100		13,100	11,300	9,000
Unamortized deferred lease costs	27,700		$ 27,700	29,700
Intangible assets, useful life			15 years
Impairment charge recognized, related to long-lived assets			$ 36,700	30,200	94,800
Provision for doubtful accounts			$ 2,909	$ 22,516	$ 896
Number of wholly owned subsidiaries that entered into intercompany loan agreement | entity			2
Intercompany loan maximum lend/borrow amount	$ 500,000	$ 750,000
Number of towers acquired | item	941	1,641	1,425	531	893
Gain (loss) on remeasurement of U.S. denominated intercompany loan			$ (8,754)	$ 90,030	$ (178,854)
Intercompany foreign currency outstanding balance	$ 560,900		$ 560,900
Oi S.A. [Member]
Summary of Significant Accounting Policies [Line Items]
Provision for doubtful accounts				$ 16,498
Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Lease term			5 years
Duration of site development projects			3 months
Business acquisitions performance target period			1 year
Maximum [Member]
Summary of Significant Accounting Policies [Line Items]
Lease term			10 years
Duration of site development projects			12 months
Business acquisitions performance target period			3 years
Site Development Revenue [Member] | Revenue [Member]
Summary of Significant Accounting Policies [Line Items]
Concentration risk percentage of revenue			6.00%