Stock-Based Compensation (Incentive Compensation Plans) (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Other incentive plans | |||
| Schedule of Incentive Compensation [Line Items] | |||
| Incentive compensation expense | $ 30 | $ 21 | $ 24 |