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LONG-TERM OBLIGATIONS - Current Portion of Long-Term Obligations (Details) € in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($)	Mar. 31, 2024 EUR (€)	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
Current portion of long-term obligations	$ 3,067.6		$ 3,187.5
Unsecured debt \| 2021 EUR Three Year Delayed Draw Term Loan
Debt Instrument [Line Items]
Debt instrument term	3 years
American Tower Corporation \| Senior Notes \| 3.375% senior notes
Debt Instrument [Line Items]
Current portion of long-term obligations	$ 650.0
Debt interest rate (as a percent)	3.375%	3.375%
American Tower Corporation \| Senior Notes \| 2.950% senior notes
Debt Instrument [Line Items]
Current portion of long-term obligations	$ 650.0
Debt interest rate (as a percent)	2.95%	2.95%
American Tower Corporation \| Senior Notes \| 2.400% senior notes
Debt Instrument [Line Items]
Current portion of long-term obligations	$ 750.0
Debt interest rate (as a percent)	2.40%	2.40%
American Tower Corporation \| Unsecured debt \| 2021 EUR Three Year Delayed Draw Term Loan
Debt Instrument [Line Items]
Current portion of long-term obligations \| €		€ 825.0
Debt instrument term	3 years