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Employee Benefits (Details) (USD $)
In Millions, unless otherwise specified |
3 Months Ended | 9 Months Ended | 3 Months Ended | 9 Months Ended | 0 Months Ended | |||||
|---|---|---|---|---|---|---|---|---|---|---|
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Sep. 30, 2012
U.S. Pension Plan
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Sep. 30, 2011
U.S. Pension Plan
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Sep. 30, 2012
U.S. Pension Plan
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Sep. 30, 2011
U.S. Pension Plan
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Sep. 30, 2012
International Pension Plan
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Sep. 30, 2011
International Pension Plan
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Sep. 30, 2012
International Pension Plan
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Sep. 30, 2011
International Pension Plan
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Oct. 01, 2012
Retirement Plans Merger
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Sep. 30, 2012
Retirement Plans Merger
item
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| Defined Benefit Plan Disclosure | ||||||||||
| Service cost | $ 4 | $ 5 | $ 12 | $ 15 | ||||||
| Interest cost | 29 | 31 | 89 | 92 | 66 | 67 | 198 | 201 | ||
| Expected return on plan assets | (31) | (30) | (95) | (90) | (80) | (73) | (241) | (217) | ||
| Amortization of net actuarial loss | 10 | 8 | 32 | 23 | 15 | 14 | 44 | 41 | ||
| Net periodic benefit cost | 8 | 9 | 26 | 25 | 5 | 13 | 13 | 40 | ||
| Estimate of contributions to defined benefit pension plans for the current fiscal year | 226 | 226 | 415 | 415 | ||||||
| Number of legacy Aon and Hewitt UK pension plans merged into one | 5 | |||||||||
| Original number of legacy Aon and Hewitt UK legacy pension plans | 7 | |||||||||
| Number of legacy Aon and Hewitt UK pension plans post merger | 1 | |||||||||
| Contributions made to defined benefit pension plans | $ 195 | $ 259 | $ 80 | |||||||
| X | ||||||||||
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- Definition
The entity's estimate of aggregate contributions expected to be paid to the defined benefit plan(s) in the current fiscal year. No definition available.
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- Definition
Represents the information pertaining to the number of Aon and Hewitt UK pension plans post merger. No definition available.
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- Definition
The number of legacy pension plans merged. No definition available.
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- Definition
The number of legacy pension plans for Aon and Hewitt UK held by the reporting entity. No definition available.
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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 increase in the fair value of plan assets from contributions made by the employer. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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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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| X | ||||||||||
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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
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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