Earnings Per Share (Schedule of Earnings Per Basic And Diluted by Common Class) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share [Abstract]
Net income attributable to American Tower Corporation stockholders	$ 156,056	$ 234,431	$ 349,373	$ 436,930
Dividends on preferred stock	(26,782)	(4,375)	(36,601)	(4,375)
NET INCOME ATTRIBUTABLE TO AMERICAN TOWER CORPORATION COMMON STOCKHOLDERS	$ 129,274	$ 230,056	$ 312,772	$ 432,555
Basic weighted average common shares outstanding (in shares)	423,154	395,872	414,182	395,511
Dilutive securities (in shares)	3,779	3,716	4,121	3,941
Diluted weighted average common shares outstanding (in shares)	426,933	399,588	418,303	399,452
Basic net income attributable to American Tower Corporation common stockholders per common share (in dollars per share)	$ 0.31	$ 0.58	$ 0.76	$ 1.09
Diluted net income attributable to American Tower Corporation common stockholders per common share (in dollars per share)	$ 0.30	$ 0.58	$ 0.75	$ 1.08