Intangible Assets - Narrative (Details) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($) unit	Dec. 31, 2023 USD ($) unit	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($) license	Dec. 31, 2020 USD ($)	Jun. 30, 2024 unit
Licenses
Cash paid for licenses		$ 20	$ 130	$ 585
FCC Licenses, number of accounting units | unit		12	1				2
Loss on impairment of licenses	$ 136	$ 136	$ 0	3
Licenses		4,579	4,693
High-band spectrum
Licenses
Licenses	$ 161
Minimum
Licenses
Wireless spectrum license fair value exceeds carrying value	9.00%
Maximum
Licenses
Wireless spectrum license fair value exceeds carrying value	80.00%
Auction 107
Licenses
Licenses won | license					254
Total winning bid					$ 1,283
FCC Upfront Payment						$ 30
Cash paid for licenses		$ 8	$ 122	$ 8	$ 36