Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2016	Sep. 30, 2015
Statement Of Financial Position [Abstract]
Accounts receivable, allowances	$ 52	$ 56
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	10,000	10,000
Common stock, shares issued	1,055	1,055
Common stock, shares outstanding	1,055	1,055