Fair Value Measurements - Schedule of Assets and Liabilities at Fair Value (Details) - Recurring - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018
Other noncurrent assets
Total assets at fair value	$ 79	$ 53
Accrued expenses and other liabilities
Total liabilities at fair value	0	1
Level 1
Other noncurrent assets
Non-qualified trust funds	20	25
Level 2
Prepaid expenses and other current assets
Currency derivatives	0	1
Accrued expenses and other liabilities
Currency derivatives	0	1
Money market funds | Level 1
Cash and cash equivalents
Cash and cash equivalents	0	5
Time deposits | Level 2
Cash and cash equivalents
Cash and cash equivalents	$ 59	$ 22