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LONG-TERM OBLIGATIONS - Bank Facilities (Details) € in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($)	Mar. 31, 2024 EUR (€)	Mar. 31, 2023 USD ($)	Feb. 14, 2024	Jan. 12, 2024
Line of Credit Facility [Line Items]
Borrowings under credit facilities	$ 2,790.5		$ 1,745.0
0.600% Senior Notes \| American Tower Corporation \| Senior Notes
Line of Credit Facility [Line Items]
Debt interest rate (as a percent)	0.60%				0.60%
5.00% Senior Notes \| American Tower Corporation \| Senior Notes
Line of Credit Facility [Line Items]
Debt interest rate (as a percent)	5.00%			5.00%
Revolving Credit Facility \| 2021 Multicurrency Credit Facility \| American Tower Corporation
Line of Credit Facility [Line Items]
Borrowings under credit facilities	$ 2,000.0
Repayment of indebtedness under credit facility	1,700.0
Line of credit maximum borrowing capacity	6,000.0
Revolving Credit Facility \| 2021 Multicurrency Credit Facility In Euros \| American Tower Corporation
Line of Credit Facility [Line Items]
Borrowings under credit facilities	339.4	€ 315.0
Repayment of indebtedness under credit facility	91.9	€ 85.0
Revolving Credit Facility \| 2021 Credit Facility \| American Tower Corporation
Line of Credit Facility [Line Items]
Borrowings under credit facilities	775.0
Repayment of indebtedness under credit facility	340.0
Line of credit maximum borrowing capacity	$ 4,000.0