Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions |
12 Months Ended | ||
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Sep. 30, 2015 |
Sep. 30, 2014 |
Sep. 30, 2013 |
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| Pension Benefits | |||
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |||
| Service cost | $ 47 | $ 46 | $ 43 |
| Interest cost | 40 | 42 | 35 |
| Expected return on assets | (72) | (68) | (61) |
| Prior service credit | (7) | (8) | (9) |
| Actuarial loss (gain) | 1 | 1 | 28 |
| Net benefit cost | 9 | 13 | 36 |
| Curtailment gain | 0 | (3) | 0 |
| Settlement loss | 7 | 3 | 0 |
| Total net periodic benefit cost | 16 | 13 | 36 |
| Other Postretirement Benefits | |||
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |||
| Service cost | 0 | 0 | 0 |
| Interest cost | 1 | 1 | 1 |
| Expected return on assets | 0 | 0 | 0 |
| Prior service credit | (3) | (3) | (3) |
| Actuarial loss (gain) | (2) | (1) | (1) |
| Net benefit cost | (4) | (3) | (3) |
| Curtailment gain | 0 | 0 | 0 |
| Settlement loss | 0 | 0 | |
| Total net periodic benefit cost | $ (4) | $ (3) | $ (3) |
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- Definition The amount of gains or losses recognized in net periodic benefit cost. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition The amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition The amount of decrease that is related to an event that significantly reduces the expected years of future service of present employees or eliminates for a significant number of employees the accrual of defined benefits for some or all of their future services. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition An amount calculated as a basis for determining the extent of delayed recognition of the effects of changes in the fair value of assets. The expected return on plan assets is determined based on the expected long-term rate of return on plan assets and the market-related value of plan assets. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount of net gain (loss) recognized in net periodic benefit cost as a result of an irrevocable action that relieves the employer (or the plan) of primary responsibility for a benefit obligation and eliminates significant risks related to the obligation and the assets used to effect the settlement. Examples of transactions that constitute a settlement include, but are not limited to, lump-sum cash payments to plan participants in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contracts to cover vested benefits. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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- Definition Defined Benefit Plan, Net Periodic Benefit Cost before Settlements and Curtailments No definition available.
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