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Intangible Assets - Schedules (Details) - Licenses - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019
Licenses |  |
Balance at beginning of year | $ 2,471 | $ 2,186
Acquisitions | 171 | 267
Divestitures | (18) | (10)
Exchanges - Licenses received | 0 | 26
Capitalized interest | 5 | 2
Balance at end of year | $ 2,629 | $ 2,471

X
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