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LONG-TERM OBLIGATIONS - Bank Facilities (Details) € in Millions, $ in Millions	6 Months Ended
	Jun. 30, 2025 USD ($)	Jun. 30, 2025 EUR (€)	Jun. 30, 2024 USD ($)	May 30, 2025	Apr. 03, 2025	Jan. 28, 2025 USD ($)	Jan. 14, 2025	Dec. 31, 2024
Line of Credit Facility [Line Items]
Borrowings under credit facilities	$ 3,632.3		$ 5,097.9
American Tower Corporation \| 2021 Term Loan \| Unsecured debt
Line of Credit Facility [Line Items]
Aggregate principal amount						$ 1,000.0
American Tower Corporation \| 2.950% senior notes \| Senior notes
Line of Credit Facility [Line Items]
Debt interest rate (as a percent)							2.95%	2.95%
American Tower Corporation \| 1.375% senior notes \| Senior notes
Line of Credit Facility [Line Items]
Debt interest rate (as a percent)					1.375%			1.375%
American Tower Corporation \| 4.000% senior notes \| Senior notes
Line of Credit Facility [Line Items]
Debt interest rate (as a percent)				4.00%				4.00%
American Tower Corporation \| Revolving Credit Facility \| 2021 Multicurrency Credit Facility
Line of Credit Facility [Line Items]
Line of credit maximum borrowing capacity						6,000.0
Borrowings under credit facilities	1,500.0
Repayment of indebtedness under credit facility	800.0
American Tower Corporation \| Revolving Credit Facility \| 2021 Credit Facility
Line of Credit Facility [Line Items]
Line of credit maximum borrowing capacity						$ 4,000.0
Borrowings under credit facilities	2,100.0
Repayment of indebtedness under credit facility	1,300.0
American Tower Corporation \| Revolving Credit Facility \| 2021 Multicurrency Credit Facility In Euros
Line of Credit Facility [Line Items]
Borrowings under credit facilities	529.1	€ 492.0
Repayment of indebtedness under credit facility	$ 549.9	€ 492.0