ACQUISITIONS - PRO FORMA INFORMATION (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Business Acquisition, Pro Forma Information [Abstract]
Pro forma operating revenues	$ 1,517,197	$ 1,449,460	$ 4,498,458	$ 4,372,304
Pro forma net income attributable to American Tower Corporation	$ 238,364	$ 72,885	$ 643,780	$ 346,097
Basic net income attributable to American Tower Corporation common stockholders (in dollars per share)	$ 0.56	$ 0.17	$ 1.52	$ 0.82
Diluted net income attributable to American Tower Corporation common stockholders (in dollars per share)	$ 0.55	$ 0.17	$ 1.50	$ 0.81

The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(2)-(3)
-URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1392-128463

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The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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