Employee Benefit Plans - Schedule of Components of Pension and Other Postretirement Benefit Costs for Continuing Operation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1	$ 2	$ 3	$ 4
Interest cost	2	2	5	5
Expected return on plan assets	(2)	(3)	(5)	(6)
Curtailment	0	0	(18)	0
Actuarial (gain) loss	0	0	0	0
Total net periodic benefit costs (income)	1	1	(15)	3
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0	1
Interest cost	1	0	1	0
Expected return on plan assets	0	0	0	0
Curtailment	0	0	0	0
Actuarial (gain) loss	0	0	0	0
Total net periodic benefit costs (income)	$ 1	$ 0	$ 1	$ 1