Postretirement, Pension and Other Employee Benefit Plans (Deferred Compensation Plans) (Details) - Deferred Compensation Plans [Member] - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |||
| Benefit obligation | $ 2,164 | $ 2,038 | $ 1,774 |
| Interest expense | 178 | 171 | 149 |
| NBCUniversal Media LLC [Member] | |||
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |||
| Benefit obligation | 494 | 417 | 349 |
| Interest expense | $ 48 | $ 28 | $ 24 |