| Document and Entity Information | Mar. 03, 2023 |
| Document And Entity Information [Line Items] | |
| Entity Registrant Name | AMERICAN TOWER CORP /MA/ |
| Amendment Flag | false |
| Entity Central Index Key | 0001053507 |
| Document Type | 8-K |
| Document Period End Date | Mar. 03, 2023 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-14195 |
| Entity Tax Identification Number | 65-0723837 |
| Entity Address, Address Line One | 116 Huntington Avenue |
| Entity Address, City or Town | Boston |
| Entity Address, State or Province | MA |
| Entity Address, Postal Zip Code | 02116 |
| City Area Code | (617) |
| Local Phone Number | 375-7500 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Common Stock [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | Common Stock, $0.01 par value |
| Trading Symbol | AMT |
| Security Exchange Name | NYSE |
| A 1375 Senior Notes Due 2025 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.375% Senior Notes due 2025 |
| Trading Symbol | AMT 25A |
| Security Exchange Name | NYSE |
| A 1950 Senior Notes Due 2026 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.950% Senior Notes due 2026 |
| Trading Symbol | AMT 26B |
| Security Exchange Name | NYSE |
| A 0450 Senior Notes Due 2027 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 0.450% Senior Notes due 2027 |
| Trading Symbol | AMT 27C |
| Security Exchange Name | NYSE |
| A 0400 Senior Notes Due 2027 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 0.400% Senior Notes due 2027 |
| Trading Symbol | AMT 27D |
| Security Exchange Name | NYSE |
| A 0500 Senior Notes Due 2028 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 0.500% Senior Notes due 2028 |
| Trading Symbol | AMT 28A |
| Security Exchange Name | NYSE |
| A 0875 Senior Notes Due 2029 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 0.875% Senior Notes due 2029 |
| Trading Symbol | AMT 29B |
| Security Exchange Name | NYSE |
| A 0950 Senior Notes Due 2030 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 0.950% Senior Notes due 2030 |
| Trading Symbol | AMT 30C |
| Security Exchange Name | NYSE |
| A 1000 Senior Notes Due 2032 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.000% Senior Notes due 2032 |
| Trading Symbol | AMT 32 |
| Security Exchange Name | NYSE |
| A 1250 Senior Notes Due 2033 [Member] | |
| Document And Entity Information [Line Items] | |
| Security 12b Title | 1.250% Senior Notes due 2033 |
| Trading Symbol | AMT 33 |
| Security Exchange Name | NYSE |
