Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Recurring - USD ($)
$ in Millions |
Sep. 30, 2018 |
Sep. 30, 2017 |
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Assets |
$ 5
|
$ 1
|
| Liabilities |
56
|
0
|
| Level 1 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Assets |
2
|
1
|
| Liabilities |
0
|
0
|
| Level 2 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Assets |
3
|
0
|
| Liabilities |
7
|
0
|
| Level 3 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Assets |
0
|
0
|
| Liabilities |
49
|
0
|
| Investments |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Assets |
2
|
1
|
| Investments | Level 1 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Assets |
2
|
1
|
| Investments | Level 2 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Assets |
0
|
0
|
| Investments | Level 3 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Assets |
0
|
0
|
| Interest rate contracts |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Assets |
3
|
0
|
| Liabilities |
7
|
0
|
| Interest rate contracts | Level 1 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Assets |
0
|
0
|
| Liabilities |
0
|
0
|
| Interest rate contracts | Level 2 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Assets |
3
|
0
|
| Liabilities |
7
|
0
|
| Interest rate contracts | Level 3 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Assets |
0
|
0
|
| Liabilities |
0
|
0
|
| Spoken acquisition Earn-outs |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Liabilities |
15
|
0
|
| Spoken acquisition Earn-outs | Level 1 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Liabilities |
0
|
0
|
| Spoken acquisition Earn-outs | Level 2 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Liabilities |
0
|
0
|
| Spoken acquisition Earn-outs | Level 3 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Liabilities |
|
0
|
| Emergence Date Warrants | Foreign currency forward contracts |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Liabilities |
34
|
0
|
| Emergence Date Warrants | Foreign currency forward contracts | Level 1 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Liabilities |
0
|
0
|
| Emergence Date Warrants | Foreign currency forward contracts | Level 2 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Liabilities |
0
|
0
|
| Emergence Date Warrants | Foreign currency forward contracts | Level 3 |
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Liabilities |
$ 34
|
$ 0
|