Other Assets - Summary of Other Assets (Details) - USD ($) $ in Millions	Dec. 31, 2017	Sep. 30, 2017
Other Assets [Abstract]
Long-term receivables	$ 204	$ 211
Investments in equity affiliates	6	7
Exchange and rental assets (net of accumulated depreciation of $109 at December 31, 2017 and $106 at September 30, 2017)	71	71
Other	248	242
Other Assets	529	531
Accumulated depreciation, exchange and rental assets	$ 109	$ 106