CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
REVENUES:
Revenue from contract with customer	$ 137.3	$ 121.9	$ 402.8	$ 365.1
Total operating revenues	1,953.6	1,785.5	5,656.6	5,308.2
Costs of operations (exclusive of items shown separately below):
Property	548.0	543.1	1,630.4	1,597.7
Services	11.9	13.6	36.2	39.2
Depreciation, amortization and accretion	442.8	448.9	1,328.6	1,344.9
Selling, general, administrative and development expense	187.9	177.9	550.8	540.7
Other operating expenses	34.7	34.8	83.5	269.6
Total operating expenses	1,225.3	1,218.3	3,629.5	3,792.1
OPERATING INCOME	728.3	567.2	2,027.1	1,516.1
OTHER INCOME (EXPENSE):
Interest income (expense), TV Azteca	0.0	0.6	0.0	(0.1)
Interest income	12.2	10.1	36.3	43.9
Interest expense	(201.3)	(209.2)	(613.3)	(616.7)
Loss on retirement of long-term obligations	0.0	0.0	(22.2)	0.0
Other income (including foreign currency (losses) gains of ($1.1), $2.2, $13.7 and ($14.9), respectively)	2.8	21.1	19.6	14.1
Total other expense	(186.3)	(177.4)	(579.6)	(558.8)
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES	542.0	389.8	1,447.5	957.3
Income tax (provision) benefit	(36.7)	(12.5)	(100.3)	14.7
NET INCOME	505.3	377.3	1,347.2	972.0
Net income attributable to noncontrolling interests	(6.7)	(10.4)	(22.1)	(13.2)
NET INCOME ATTRIBUTABLE TO AMERICAN TOWER CORPORATION STOCKHOLDERS	498.6	366.9	1,325.1	958.8
Dividends on preferred stock	0.0	0.0	0.0	(9.4)
NET INCOME ATTRIBUTABLE TO AMERICAN TOWER CORPORATION COMMON STOCKHOLDERS	$ 498.6	$ 366.9	$ 1,325.1	$ 949.4
NET INCOME PER COMMON SHARE AMOUNTS:
Basic net income attributable to American Tower Corporation common stockholders (in dollars per share)	$ 1.13	$ 0.83	$ 3.00	$ 2.16
Diluted net income attributable to American Tower Corporation common stockholders (in dollars per share)	$ 1.12	$ 0.83	$ 2.98	$ 2.15
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING (in thousands):
BASIC (in shares)	442,763	440,889	442,110	439,191
DILUTED (in shares)	445,829	444,121	445,352	442,468
Property Revenue [Member]
REVENUES:
Total operating revenues	$ 1,921.6	$ 1,751.6	$ 5,556.5	$ 5,211.4
Services revenue
REVENUES:
Revenue from contract with customer	$ 32.0	$ 33.9	$ 100.1	$ 96.8