Leases - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 14, 2020 USD ($) tower_site
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets	$ 28,021	$ 10,933
Lease liabilities	30,587
Interest payments for financing leases	79	$ 82
Additional operating leases not yet commenced, payments due	$ 227
American Tower
Lessee, Lease, Description [Line Items]
Number of licensed towers | tower_site			20,729
Operating lease right-of-use assets			$ 11,000
Lease liabilities			$ 11,000