Income Taxes	3 Months Ended
Mar. 31, 2013
Income Tax Expense (Benefit) [Abstract]
Income Taxes	We had gross unrecognized tax benefits of $53.1 million and $53.4 million at March 31, 2013 and December 31, 2012. The amount of net unrecognized tax benefits that, if recognized, would affect the effective tax rate is $29.9 million and $28.1 million at March 31, 2013 and December 31, 2012. At March 31, 2013, we believe that it is reasonably possible that the gross unrecognized tax benefits could decrease by up to $11.7 million in the next twelve months due to settlements or the expiration of statutes of limitations. We continually evaluate expiring statutes of limitations, audits, proposed settlements, changes in tax laws and new authoritative rulings. We recognize accrued interest and penalties associated with uncertain tax positions as a component of the income tax provision. As of December 31, 2012, accrued interest and penalties associated with uncertain tax positions were $24.6 million and $12.0 million. During the three months ended March 31, 2013, we accrued an additional $1.4 million in interest and accrued an additional $0.1 million in penalties associated with uncertain tax positions. Since October 1, 2010, we have been included in GM's consolidated U.S. federal income tax returns. These tax years are subject to examination by the Internal Revenue Service ("IRS"). Similarly, we also file unitary, combined or consolidated state and local tax returns with GM in certain jurisdictions. We continue to file separate returns in those state, local and foreign taxing jurisdictions where filing a separate return is mandated. Prior to October 1, 2010, we filed income tax returns with the U.S. federal government and with various state, local and foreign jurisdictions. Our federal income tax returns for fiscal 2006 through 2010 are under audit by the IRS and have been submitted to Congressional Joint Committee on Taxation (“JCT”) for review. Per a notice dated April 10, 2013, the JCT has completed its review and has taken no exception to the conclusions reached by the IRS. The completion of the JCT review will be reflected on the June 30, 2013 financial statements and does not have a significant impact. With few exceptions, we are no longer subject to state and local, or non-U.S. income tax examinations by tax authorities prior to fiscal 2005. Certain of our state tax returns are currently under examination in various state tax jurisdictions. For taxable income recognized by us in any period beginning on or after October 1, 2010, we are obligated to pay GM for our share of the consolidated federal and state tax liabilities. Likewise, GM is obligated to reimburse us for the tax effects of net operating losses to the extent such losses could be carried back as if we had filed separate income tax returns. Amounts owed to GM for income taxes are accrued and recorded as a related party payable. Under our tax sharing arrangement with GM, amended effective April 1, 2013, payments for the tax years 2010 through 2014 are deferred for four years from their original due date, with the first payment due December 15, 2014.The total amount of deferral cannot exceed $1.0 billion. Any difference between the amounts paid under our tax sharing arrangement with GM and our separate return basis used for financial reporting purposes is reported in our consolidated financial statements as additional paid-in capital. As of March 31, 2013, a cumulative difference of $0.8 million between the amounts to be paid under our tax sharing arrangement with GM and our separate return basis used for financial reporting purposes was reported in our consolidated financial statements through additional paid-in capital. As of March 31, 2013, we have recorded related party taxes payable to GM in the amount of $594.8 million, representing the tax effects of income earned subsequent to the merger with GM. Our effective income tax rate was 37.6% and 38.1% for the three months ended March 31, 2013 and 2012.

We had gross unrecognized tax benefits of $53.1 million and $53.4 million at March 31, 2013 and December 31, 2012. The amount of net unrecognized tax benefits that, if recognized, would affect the effective tax rate is $29.9 million and $28.1 million at March 31, 2013 and December 31, 2012.

At March 31, 2013, we believe that it is reasonably possible that the gross unrecognized tax benefits could decrease by up to $11.7 million in the next twelve months due to settlements or the expiration of statutes of limitations. We continually evaluate expiring statutes of limitations, audits, proposed settlements, changes in tax laws and new authoritative rulings.

We recognize accrued interest and penalties associated with uncertain tax positions as a component of the income tax provision. As of December 31, 2012, accrued interest and penalties associated with uncertain tax positions were $24.6 million and $12.0 million. During the three months ended March 31, 2013, we accrued an additional $1.4 million in interest and accrued an additional $0.1 million in penalties associated with uncertain tax positions.

Since October 1, 2010, we have been included in GM's consolidated U.S. federal income tax returns. These tax years are subject to examination by the Internal Revenue Service ("IRS"). Similarly, we also file unitary, combined or consolidated state and local tax returns with GM in certain jurisdictions. We continue to file separate returns in those state, local and foreign taxing jurisdictions where filing a separate return is mandated. Prior to October 1, 2010, we filed income tax returns with the U.S. federal government and with various state, local and foreign jurisdictions. Our federal income tax returns for fiscal 2006 through 2010 are under audit by the IRS and have been submitted to Congressional Joint Committee on Taxation (“JCT”) for review. Per a notice dated April 10, 2013, the JCT has completed its review and has taken no exception to the conclusions reached by the IRS. The completion of the JCT review will be reflected on the June 30, 2013 financial statements and does not have a significant impact. With few exceptions, we are no longer subject to state and local, or non-U.S. income tax examinations by tax authorities prior to fiscal 2005. Certain of our state tax returns are currently under examination in various state tax jurisdictions.

For taxable income recognized by us in any period beginning on or after October 1, 2010, we are obligated to pay GM for our share of the consolidated federal and state tax liabilities. Likewise, GM is obligated to reimburse us for the tax effects of net operating losses to the extent such losses could be carried back as if we had filed separate income tax returns. Amounts owed to GM for income taxes are accrued and recorded as a related party payable. Under our tax sharing arrangement with GM, amended effective April 1, 2013, payments for the tax years 2010 through 2014 are deferred for four years from their original due date, with the first payment due December 15, 2014.The total amount of deferral cannot exceed $1.0 billion. Any difference between the amounts paid under our tax sharing arrangement with GM and our separate return basis used for financial reporting purposes is reported in our consolidated financial statements as additional paid-in capital. As of March 31, 2013, a cumulative difference of $0.8 million between the amounts to be paid under our tax sharing arrangement with GM and our separate return basis used for financial reporting purposes was reported in our consolidated financial statements through additional paid-in capital. As of March 31, 2013, we have recorded related party taxes payable to GM in the amount of $594.8 million, representing the tax effects of income earned subsequent to the merger with GM.

Our effective income tax rate was 37.6% and 38.1% for the three months ended March 31, 2013 and 2012.