Investments - Narrative (Details) - USD ($) |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2018 |
Sep. 30, 2018 |
Sep. 30, 2017 |
Dec. 31, 2017 |
|
| Investments [Abstract] | ||||
| Investment securities in a continuous loss position for greater than 12 months, estimated fair value | $ 696,000,000 | $ 696,000,000 | $ 360,000,000 | |
| Investment securities in a continuous loss position for greater than 12 months, unrealized losses | 14,000,000 | 14,000,000 | $ 0 | |
| Business Acquisition [Line Items] | ||||
| Gain on sale | $ 572,000,000 | $ 21,000,000 | ||
| Glosis | ||||
| Business Acquisition [Line Items] | ||||
| Gain on relinquishment of investment | 266,000,000 | |||
| Flipkart [Member] | ||||
| Business Acquisition [Line Items] | ||||
| Gain on sale | $ 313,000,000 | |||