Acquisitions (Schedule Of Acquisition Capital Expenditures) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Acquisitions [Abstract]
Towers and related intangible assets	$ 66,338	$ 31,022	$ 124,476	$ 144,534
Land buyouts and other assets	12,488	11,676	36,531	46,868
Total cash acquisition capital expenditures	78,826	42,698	161,007	191,402
Acquisition costs paid through the issuance of common stock			$ 63,300
Common stock issued for acquisition costs			487,963
Unfunded towers and related intangible assets acquisitions	21,000		$ 21,000
Ground lease extensions	$ 2,400	$ 2,200	$ 10,600	$ 8,700