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, 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 | 2,238 | $ 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 | $ 513 | $ 608 | |||