Severance and Leased Real Estate (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
Jun. 30, 2013
Severance
Restructuring reserve
Balance at the beginning of the period	$ 17
Accrued to expense	13
Payments, net	(18)
Balance at the end of the period	12
Leased real estate
Restructuring reserve
Balance at the beginning of the period	131
Payments, net	(8)
Reversals and adjustments	(2)
Balance at the end of the period	121
Current portion of leased real estate accrual	18
Noncurrent portion of leased real estate accrual	$ 103
Ceased-use leased real estate accrual \| Leased real estate \| Minimum
Restructuring reserve
Remaining lease terms	2 months 1 day
Ceased-use leased real estate accrual \| Leased real estate \| Maximum
Restructuring reserve
Remaining lease terms	12 years 6 months
Ceased-use leased real estate accrual \| Leased real estate \| Weighted average
Restructuring reserve
Weighted average lease terms	8 years 10 months 24 days

Amount charged against earnings in the period for incurred and estimated costs associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, excluding asset retirement obligations.

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Amount of any reversal and other adjustment made during the period to the amount of a previously accrued liability for a specified type of restructuring cost, excluding adjustments for costs incurred during the period, costs settled during the period, and foreign currency translation adjustments.

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- Definition

Carrying amount as of the balance sheet date of known and estimated obligations associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, which are expected to be paid in the next twelve months or in the normal operating cycle if longer. Costs of such activities include those for one-time termination benefits, termination of an operating lease or other contract, consolidating or closing facilities, relocating employees, and costs associated with an ongoing benefit arrangement, but excludes costs associated with the retirement of a long-lived asset.

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- Definition

Carrying amount as of the balance sheet date of known and estimated costs associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, which are expected to be paid after one year or beyond the next operating cycle, if longer. Costs of such activities include those for one-time termination benefits, termination of an operating lease or other contract, consolidating or closing facilities, and relocating employees, and costs associated with an ongoing benefit arrangement, but excludes costs associated with the retirement of a long-lived asset.

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- Definition

Amount of cash paid in the period to fully or partially settle a specified, previously accrued type of restructuring cost.

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