Related Party Transactions - Receivables From Related Parties (Details) - USD ($) $ in Millions |
Mar. 31, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Related Party Transaction [Line Items] | ||
| Current receivables from related parties | $ 52 | $ 36 |
| PFJ Southeast | ||
| Related Party Transaction [Line Items] | ||
| Current receivables from related parties | 30 | 28 |
| Sherwood Midstream Holdings | ||
| Related Party Transaction [Line Items] | ||
| Current receivables from related parties | 15 | 0 |
| Other equity method investees | ||
| Related Party Transaction [Line Items] | ||
| Current receivables from related parties | $ 7 | $ 8 |