Income Taxes	3 Months Ended
Mar. 31, 2012
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes For the three months ended March 31, 2012, the income tax expense of $64 million resulted primarily from tax expense attributable to profitable foreign entities. The effective tax rate is lower than the blended worldwide statutory tax rate primarily because the tax effects of income earned in the United States and certain foreign jurisdictions have been offset by loss carryforwards for which a tax benefit has not previously been recognized. For the three months ended March 31, 2011, the income tax benefit of $70 million resulted primarily from the $101 million reversal of valuation allowance on net deferred tax assets in one of our Canadian subsidiaries offset partially by tax expense attributable to profitable foreign entities. The valuation allowance reversal related to modifications to the structure of our Canadian operations. A sustained period of profitability in our U.S. operations is required before we would change our judgment regarding the need for a full valuation allowance against our net U.S. deferred tax assets. Continued improvement in our U.S. operating results throughout 2012 could lead to the reversal of a portion of our U.S. valuation allowance.

Income Taxes

3 Months Ended

Mar. 31, 2012

For the three months ended March 31, 2012, the income tax expense of $64 million resulted primarily from tax expense attributable to profitable foreign entities. The effective tax rate is lower than the blended worldwide statutory tax rate primarily because the tax effects of income earned in the United States and certain foreign jurisdictions have been offset by loss carryforwards for which a tax benefit has not previously been recognized.

For the three months ended March 31, 2011, the income tax benefit of $70 million resulted primarily from the $101 million reversal of valuation allowance on net deferred tax assets in one of our Canadian subsidiaries offset partially by tax expense attributable to profitable foreign entities. The valuation allowance reversal related to modifications to the structure of our Canadian operations.

A sustained period of profitability in our U.S. operations is required before we would change our judgment regarding the need for a full valuation allowance against our net U.S. deferred tax assets. Continued improvement in our U.S. operating results throughout 2012 could lead to the reversal of a portion of our U.S. valuation allowance.