Income Taxes - Schedule of Income Tax Expense and Effective Tax Rate (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income tax expense	$ 25	$ 17	$ 49	$ 36
Effective tax rate percentage	28.40%	21.30%	26.50%	23.70%