Selected Quarterly Financial Data (Schedule Of Quarterly Financial Information) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Selected Quarterly Financial Information [Abstract]
Operating revenues	$ 941,969		$ 807,880		$ 808,830		$ 802,728		$ 768,374		$ 713,335		$ 697,734		$ 696,517		$ 3,361,407		$ 2,875,960		$ 2,443,532
Cost of operations	251,569	[1]	200,829	[1]	205,709	[1]	201,766	[1]	194,206	[1]	184,904	[1]	172,384	[1]	170,985	[1]	859,873	[1]	722,479	[1]
Operating income	292,928		308,879		312,812		299,686		279,235		295,552		270,486		274,446		1,214,305		1,119,719		920,132
Net income	73,925		163,222		84,113		160,948		118,153		231,825		33,689		210,358		482,208		594,025		381,840
Net income attributable to American Tower Corporation	$ 99,982		$ 180,123		$ 99,821		$ 171,407		$ 135,679		$ 232,089		$ 48,209		$ 221,306		$ 551,333		$ 637,283		$ 396,462
Basic net income per common share (in dollars per share)	$ 0.25		$ 0.46		$ 0.25		$ 0.43		$ 0.34		$ 0.59		$ 0.12		$ 0.56		$ 1.40		$ 1.61		$ 1.00
Diluted net income per common share (in dollars per share)	$ 0.25		$ 0.45		$ 0.25		$ 0.43		$ 0.34		$ 0.58		$ 0.12		$ 0.56		$ 1.38		$ 1.60		$ 0.99

[1] Represents Operating expenses, exclusive of Depreciation, amortization and accretion, Selling, general, administrative and development expense, and Other operating expense.