Segment Information - Total Revenue by Geographic Region (Detail) - 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 | $ 2,863 | $ 2,910 | $ 2,905 | $ 2,723 | $ 2,784 | $ 2,849 | $ 2,778 | $ 2,670 | $ 11,401 | $ 11,081 | $ 10,180 |
| Americas [Member] | |||||||||||
| Segment Reporting Information [Line Items] | |||||||||||
| Revenue | 7,502 | 7,286 | 6,829 | ||||||||
| Europe [Member] | |||||||||||
| Segment Reporting Information [Line Items] | |||||||||||
| Revenue | 3,356 | 3,246 | 2,832 | ||||||||
| Asia-Pacific [Member] | |||||||||||
| Segment Reporting Information [Line Items] | |||||||||||
| Revenue | $ 543 | $ 549 | $ 519 | ||||||||