Segment Information - Total Revenue by Geographic Region (Detail) - USD ($) $ in Millions |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2019 |
Sep. 30, 2019 |
Jun. 30, 2019 |
Mar. 31, 2019 |
Dec. 31, 2018 |
Sep. 30, 2018 |
Jun. 30, 2018 |
Mar. 31, 2018 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| Segment Reporting Information [Line Items] | |||||||||||
| Revenue | $ 3,977 | $ 3,692 | $ 3,524 | $ 3,346 | $ 3,434 | $ 3,576 | $ 3,605 | $ 3,583 | $ 14,539 | $ 14,198 | $ 13,600 |
| Americas [Member] | |||||||||||
| Segment Reporting Information [Line Items] | |||||||||||
| Revenue | 9,703 | 9,303 | 8,798 | ||||||||
| Europe [Member] | |||||||||||
| Segment Reporting Information [Line Items] | |||||||||||
| Revenue | 4,158 | 4,217 | 4,126 | ||||||||
| Asia-Pacific [Member] | |||||||||||
| Segment Reporting Information [Line Items] | |||||||||||
| Revenue | $ 678 | $ 678 | $ 676 | ||||||||