Benefit Obligations in Excess of Plan Assets Related to the Company's U.S. Non-Qualified Plan and the Non-U.S. Pension Plans (Detail) - Pension Benefits - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017
U.S. Plans
Accumulated benefit obligation in excess of plan assets
Accumulated benefit obligation—end of year	$ (6)	$ (7)
Fair value of plan assets—end of year	0	0
Projected benefit obligation in excess of plan assets
Benefit obligation—end of year	(6)	(7)
Fair value of plan assets—end of year	0	0
Non-U.S. Plans
Accumulated benefit obligation in excess of plan assets
Accumulated benefit obligation—end of year	(452)	(5)
Fair value of plan assets—end of year	436	0
Projected benefit obligation in excess of plan assets
Benefit obligation—end of year	(452)	(5)
Fair value of plan assets—end of year	$ 436	$ 0