Divestiture - Results of Discontinued Operations (Detail) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Discontinued Operations and Disposal Groups [Abstract]
Revenues	$ 0	$ 0	$ 20
Income from discontinued operations before income taxes	0	0	586
Less income tax provision	0	0	222
Income from discontinued operations, net	$ 0	$ 0	$ 364

Amount before tax of income (loss) from a discontinued operation. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

Amount of tax expense (benefit) related to a discontinued operation. Includes, but is not limited to, tax expense (benefit) related to income (loss) from operations during the phase-out period, tax expense (benefit) related to gain (loss) on disposal, tax expense (benefit) related to gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and tax expense (benefit) related to adjustments of a prior period gain (loss) on disposal.

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- Definition

Amount after tax of income (loss) from a discontinued operation including the portion attributable to the noncontrolling interest. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

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