Income Tax (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010
Gross deferred tax assets on tax loss carryforwards and investment credits expiration
2012	$ 42
2013	23
2014	21
2015	16
2016	77
Thereafter	464
Total	643	609
Reconciliation of beginning and ending amount of unrecognized tax benefits
Beginning Balance	149	193
Additions based on tax positions related to the current year	36	44
Additions for tax positions of prior years	19	5
Reductions for tax positions of prior years	(3)	(44)
Settlements	0	(36)
Reductions for lapse of statute of limitations	(50)	(1)
Foreign currency translation	(3)	(12)
Ending Balance	$ 148	$ 149

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Deferred Tax Assets On Tax Loss Carryforwards And Investment Credits Expiration Year Five

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Deferred tax assets on tax loss carryforwards and investment credits expiration Year Three.

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The sum of the tax effects as of the balance sheet date of the amount of excesses of tax deductions over gross income in a year which cannot be used on the tax returns in the current year but can be carried forward to reduce taxable income or income taxes payable in a future year, for which there must be sufficient tax-basis income to utilize a portion or all of the carryforward amount to realize the deferred tax asset.

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The gross amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns as of the balance sheet date.

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The gross amount of decreases in unrecognized tax benefits resulting from settlements with taxing authorities.

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The gross amount of decreases in unrecognized tax benefits resulting from lapses of the applicable statutes of limitations.

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