Significant Transactions (FCC Spectrum Auction) (Details) - FCC Spectrum [Member] - USD ($) $ in Millions |
1 Months Ended | 12 Months Ended | ||||
|---|---|---|---|---|---|---|
Jul. 31, 2017 |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Jun. 30, 2017 |
|
| FCC Spectrum Auction [Line Items] | ||||||
| Proceeds from FCC spectrum auction | $ 482 | |||||
| Gain on sale of spectrum rights | $ 337 | |||||
| Amount of spectrum acquired | $ 2,337 | $ 2,333 | $ 1,700 | |||
| Deposit to acquire intangible asset | $ 1,800 | |||||
| NBCUniversal Media LLC [Member] | ||||||
| FCC Spectrum Auction [Line Items] | ||||||
| Proceeds from FCC spectrum auction | $ 482 | |||||
| Gain on sale of spectrum rights | $ 337 | |||||
| Amount of spectrum acquired | $ 612 | $ 608 | ||||