LONG-TERM OBLIGATIONS - Repayments of Senior Notes (Details) - American Tower Corporation € in Millions, $ in Millions	Sep. 12, 2025 USD ($)	May 30, 2025 USD ($)	Apr. 03, 2025 EUR (€)	Mar. 14, 2025 USD ($)	Jan. 14, 2025 USD ($)	Sep. 30, 2025 USD ($)	Sep. 16, 2025	Dec. 31, 2024 USD ($)
Debt Instrument [Line Items]
Debt outstanding						$ 35,428.6		$ 34,174.9
2.950% senior notes \| Senior notes
Debt Instrument [Line Items]
Debt interest rate (as a percent)					2.95%			2.95%
Aggregate principal amount repaid					$ 650.0
Debt outstanding						0.0		$ 650.0
2.400% senior notes \| Senior notes
Debt Instrument [Line Items]
Debt interest rate (as a percent)				2.40%				2.40%
Aggregate principal amount repaid				$ 750.0
Debt outstanding						$ 0.0		$ 749.7
4.900% senior notes \| Senior notes
Debt Instrument [Line Items]
Debt interest rate (as a percent)						4.90%	4.90%
Debt outstanding						$ 847.9		0.0
5.350% Senior Notes \| Senior notes
Debt Instrument [Line Items]
Debt interest rate (as a percent)						5.35%	5.35%
Debt outstanding						$ 731.5		$ 0.0
1.375% senior notes \| Senior notes
Debt Instrument [Line Items]
Debt interest rate (as a percent)			1.375%					1.375%
Aggregate principal amount repaid \| €			€ 500.0
Debt outstanding						0.0		$ 517.3
4.000% senior notes \| Senior notes
Debt Instrument [Line Items]
Debt interest rate (as a percent)		4.00%						4.00%
Aggregate principal amount repaid		$ 750.0
Debt outstanding						0.0		$ 749.4
1.300% senior notes \| Senior notes
Debt Instrument [Line Items]
Debt interest rate (as a percent)	1.30%							1.30%
Aggregate principal amount repaid	$ 500.0
Debt outstanding						$ 0.0		$ 499.3