Background and Basis of Presentation - Narrative (Details) $ in Millions |
12 Months Ended | ||||
|---|---|---|---|---|---|
|
Jul. 14, 2017
segment
|
Jul. 13, 2017
segment
|
Sep. 30, 2018
USD ($)
segment
|
Dec. 16, 2017
USD ($)
|
Dec. 15, 2017
USD ($)
|
|
| General Disclosures [Line Items] | |||||
| Number of segments | segment | 2 | 3 | 2 | ||
| Cash and cash equivalents | $ 700 | $ 366 | $ 366 | ||
| Adjustments | |||||
| General Disclosures [Line Items] | |||||
| Cash and cash equivalents | $ 26 |