Segment Data (Narrative) (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) segment	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Segment Reporting Information [Line Items]
Number of business segments | segment	2
Site leasing	$ 452,183	$ 430,542
Total assets	9,312,759		$ 7,213,707
Brazil [Member]
Segment Reporting Information [Line Items]
Site leasing	56,000	$ 61,200
Total assets	$ 1,005,600		$ 1,031,600