Investments (Cost Method Investments) (Details) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Vox Media [Member] | ||
| Cost Method Investments,Original Cost | $ 200 | |
| Vox Media [Member] | NBCUniversal Media LLC [Member] | ||
| Cost Method Investments,Original Cost | 200 | |
| BuzzFeed [Member] | ||
| Cost Method Investments,Original Cost | 200 | |
| BuzzFeed [Member] | NBCUniversal Media LLC [Member] | ||
| Cost Method Investments,Original Cost | 200 | |
| Air Touch [Member] | ||
| Fair value of AirTouch preferred stock related to redeemable preferred shares | 1,700 | $ 1,700 |
| Aggregate redemption value | 1,750 | |
| Carrying amount of redeemable preferred stock | 1,600 | 1,600 |
| Fair value of redeemable preferred shares | 1,700 | 1,700 |
| Nonredeemable preferred stock | 100 | $ 100 |
| Preferred Shares Redeemable in April 2020 [Member] | ||
| Aggregate redemption value | $ 1,650 |