Equity (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2011 years	Dec. 31, 2010	Dec. 31, 2009
Employee Stock Ownership Plan
ESOP shares allocated to plan participants		13.4
Total matching costs met with suspense shares		$ 12	$ 12
Total matching cost for all ESOP plans	44	43	41
Other Stock-Based Compensation Plans
Share authorized for other stock-based compensation plans	20
Total fair value of awards vested	24	24	16
Weighted-average grant date fair value of awards vested	$ 39.16
Total recognized expense for other stock-based compensation plans	33	27	37
Recognized tax benefit for other stock-based compensation plans	13	11	14
Total unrecognized compensation costs related to nonvested other stock-based compensation plan awards	33
Weighted-average period that total unrecognized compensation costs related to nonvested other stock-based compensation plan awards will be recognized	1.6
Accumulated other comprehensvie loss [Details]
Cash flow hedges	(143)	(63)
Pension and other postretirement benefits	(22)	(62)
Total accumulated other comprehensive loss	$ (165)	$ (125)

The total matching costs for all ESOP plans sponsored by the Company.

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Equity-based, other than a stock (or unit) option plans, gross compensation cost recognized during the period with respect to the award.

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Accumulated change, net of tax, in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's Increase or Decrease in deferred hedging gains or losses.

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As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

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The shares or units in an ESOP trust that have been assigned to individual participant accounts based on a known formula. IRS rules require allocations to be nondiscriminatory generally based on compensation, length of service, or a combination of both. For any particular participant such shares or units may be vested, unvested, or partially vested.

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The total fair value of equity-based awards for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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