Acquisitions (Schedule Of Acquisition Capital Expenditures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Acquisitions [Abstract]
Towers and related intangible assets	$ 214,686	$ 525,802	$ 1,540,258
Land buyouts and other assets	62,149	83,728	44,964
Total cash acquisition capital expenditures	276,835	609,530	1,585,222
Ground lease extensions	$ 14,100	$ 16,300	$ 10,800