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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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LONG-TERM OBLIGATIONS - BRIDGE FACILITY (Details) $ in Billions	Sep. 30, 2021	May 21, 2021	Feb. 10, 2021 USD ($)	Feb. 10, 2021 EUR (€)	Jan. 13, 2021 USD ($)	Jan. 13, 2021 EUR (€)
American Tower Corporation \| 0.450% Senior Notes due 2027 \| Senior notes
Line of Credit Facility [Line Items]
Contractual Interest Rate	0.45%	0.45%
American Tower Corporation \| 0.875% Senior Notes due 2029 \| Senior notes
Line of Credit Facility [Line Items]
Contractual Interest Rate	0.875%	0.875%
American Tower Corporation \| 1.250% Senior Notes due 2033 \| Senior notes
Line of Credit Facility [Line Items]
Contractual Interest Rate	1.25%	1.25%
Credit Facility
Line of Credit Facility [Line Items]
Line of credit maximum borrowing capacity			$ 3.9	€ 3,225,000,000
Credit Facility \| Bridge Loan
Line of Credit Facility [Line Items]
Line of credit maximum borrowing capacity			$ 5.2	€ 4,275,000,000	$ 9.1	€ 7,500,000,000