BUSINESS SEGMENTS - Summary of Geographic Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	$ 10,644.6	$ 10,127.2	$ 10,012.2
Long-lived assets held	47,142.5	45,299.2
U.S. & Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	5,588.3	5,441.8	5,359.2
U.S. & Canada \| Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	12.0	13.3	11.7
Long-lived assets held	205.8	200.5
U.S. & Canada \| United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	6,629.4	6,353.3	6,182.2
Long-lived assets held	28,333.1	28,214.3
Africa & APAC
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	1,422.9	1,208.0	1,244.4
Africa & APAC \| Australia
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	0.0	2.6	2.6
Africa & APAC \| Bangladesh
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	11.0	7.9	5.7
Long-lived assets held	24.5	30.2
Africa & APAC \| New Zealand
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	0.0	1.6	1.6
Africa & APAC \| Philippines
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	10.4	9.2	8.9
Long-lived assets held	27.7	30.2
Africa & APAC \| Burkina Faso
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	56.5	40.1	38.1
Long-lived assets held	248.4	230.9
Africa & APAC \| Ghana
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	182.8	126.7	128.6
Long-lived assets held	225.9	244.9
Africa & APAC \| Kenya
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	177.6	141.1	120.0
Long-lived assets held	665.4	672.7
Africa & APAC \| Niger
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	52.4	51.3	48.4
Long-lived assets held	193.8	177.1
Africa & APAC \| Nigeria
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	461.7	384.4	495.4
Long-lived assets held	385.8	325.4
Africa & APAC \| South Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	172.6	174.0	157.9
Long-lived assets held	258.8	327.4
Africa & APAC \| Uganda
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	297.9	269.1	237.2
Long-lived assets held	948.9	939.1
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	937.7	834.7	775.6
Europe \| France
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	130.3	121.7	113.4
Long-lived assets held	1,432.6	1,265.6
Europe \| Germany
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	455.5	402.2	363.6
Long-lived assets held	6,208.4	5,429.5
Europe \| Poland
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	0.0	0.0	0.6
Europe \| Spain
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	351.9	310.8	298.0
Long-lived assets held	3,213.9	2,834.8
Latin America
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	1,642.6	1,717.9	1,798.3
Latin America \| Argentina
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	43.6	36.2	43.8
Long-lived assets held	179.0	185.3
Latin America \| Brazil
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	708.3	786.1	787.3
Long-lived assets held	1,756.2	1,592.1
Latin America \| Chile
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	117.4	103.7	106.3
Long-lived assets held	560.4	510.1
Latin America \| Colombia
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	122.2	110.4	117.0
Long-lived assets held	264.7	231.2
Latin America \| Costa Rica
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	25.7	25.3	24.7
Long-lived assets held	101.3	106.8
Latin America \| Mexico
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	508.9	544.9	611.8
Long-lived assets held	931.2	859.1
Latin America \| Paraguay
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	17.6	16.3	16.3
Long-lived assets held	103.1	86.4
Latin America \| Peru
Revenues from External Customers and Long-Lived Assets [Line Items]
Total operating revenues	98.9	95.0	$ 91.1
Long-lived assets held	$ 873.6	$ 805.6

AMERICAN TOWER CORP /MA/ 10-K