Financing - Schedule of Temporary Equity (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Temporary Equity [Line Items] | |||
| Redeemable preferred stock | $ 324 | $ 324 | |
| Increase (Decrease) in Temporary Equity [Roll Forward] | |||
| Beginning balance | 324 | ||
| Redeemed | (33) | (658) | $ 0 |
| Issuance costs | (6) | ||
| Ending balance | 291 | 324 | |
| Redeemable Preferred Stock | |||
| Temporary Equity [Line Items] | |||
| Redeemable preferred stock | 324 | 118 | 118 |
| Increase (Decrease) in Temporary Equity [Roll Forward] | |||
| Beginning balance | 324 | 118 | 118 |
| Issued | 250 | ||
| Redeemed | (33) | (38) | |
| Ending balance | $ 291 | $ 324 | $ 118 |