Concentration of Credit Risk (Summary of Significant Customers and Percentage of Total Revenue for Specified Time Periods Derived from Such Customers) (Details) - Revenue [Member]	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
AT&T [Member]
Concentration Risk [Line Items]
Concentration risk percentage	23.80%	24.00%	25.00%
T-Mobile [Member]
Concentration Risk [Line Items]
Concentration risk percentage	18.20%	16.40%	16.50%
Sprint [Member]
Concentration Risk [Line Items]
Concentration risk percentage	16.90%	17.90%	15.10%
Verizon [Member]
Concentration Risk [Line Items]
Concentration risk percentage	14.00%	14.70%	15.20%
Domestic Site Leasing [Member] | AT&T [Member]
Concentration Risk [Line Items]
Concentration risk percentage	32.10%	31.90%	32.70%
Domestic Site Leasing [Member] | T-Mobile [Member]
Concentration Risk [Line Items]
Concentration risk percentage	21.60%	20.30%	19.70%
Domestic Site Leasing [Member] | Sprint [Member]
Concentration Risk [Line Items]
Concentration risk percentage	19.00%	19.60%	18.90%
Domestic Site Leasing [Member] | Verizon [Member]
Concentration Risk [Line Items]
Concentration risk percentage	18.60%	19.00%	19.00%
International Site Leasing [Member] | Oi S.A. [Member]
Concentration Risk [Line Items]
Concentration risk percentage	31.30%	35.50%	42.20%
International Site Leasing [Member] | Telefonica [Member]
Concentration Risk [Line Items]
Concentration risk percentage	26.90%	26.70%	25.70%
International Site Leasing [Member] | Claro [Member]
Concentration Risk [Line Items]
Concentration risk percentage	11.60%	11.40%	10.00%
Site Development Revenue [Member]
Concentration Risk [Line Items]
Concentration risk percentage	8.00%
Site Development Revenue [Member] | T-Mobile [Member]
Concentration Risk [Line Items]
Concentration risk percentage	30.20%	16.40%	26.90%
Site Development Revenue [Member] | Sprint [Member]
Concentration Risk [Line Items]
Concentration risk percentage	37.30%	47.10%	12.90%
Site Development Revenue [Member] | Verizon [Member]
Concentration Risk [Line Items]
Concentration risk percentage	2.90%	6.40%	12.80%
Site Development Revenue [Member] | Nokia, Inc. [Member]
Concentration Risk [Line Items]
Concentration risk percentage	4.30%	3.20%	10.10%