Description of Business, Including Segment and Geographic Area Information - Schedule of Revenue by Geographic Area (Parenthetical) (Details) - USD ($) $ in Millions |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2015 |
Sep. 30, 2015 |
Jun. 30, 2015 |
Mar. 31, 2015 |
Dec. 31, 2014 |
Sep. 30, 2014 |
Jun. 30, 2014 |
Mar. 31, 2014 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Segment Reporting Information [Line Items] | |||||||||||
| Revenue | $ 3,189 | $ 3,429 | $ 3,232 | $ 3,150 | $ 3,269 | $ 3,501 | $ 3,292 | $ 2,983 | $ 13,000 | $ 13,045 | $ 12,205 |
| China (including Hong Kong) | |||||||||||
| Segment Reporting Information [Line Items] | |||||||||||
| Revenue | $ 5,800 | $ 5,700 | $ 5,200 | ||||||||