Goodwill and Other Intangibles - Additional Information (Details) $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
Other intangible assets, net of accumulated amortization	$ 40	$ 40
Accumulated amortization on intangible assets	7	7
Amortization expense on intangible assets	$ 1	$ 3