Income Taxes	9 Months Ended
Sep. 30, 2014
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The combined federal, state and foreign income tax rate was 33 percent and 32 percent for the three months ended September 30, 2014 and 2013, respectively, and 34 percent for both the nine months ended September 30, 2014 and 2013. The effective tax rate for the three and nine months ended September 30, 2014 and 2013 is slightly less than the U.S. statutory rate of 35 percent primarily due to certain permanent benefit differences, including the domestic manufacturing deduction, partially offset by state and local tax expense. Prior to the June 30, 2011 spinoff transaction from Marathon Oil Corporation (“Marathon Oil”), we were included in Marathon Oil’s income tax returns for all applicable years. During 2011, we anticipated a future settlement between Marathon Oil and us upon the filing of Marathon Oil’s consolidated U.S. federal and state income tax returns for the period prior to June 30, 2011. During the second quarter of 2013, we settled with Marathon Oil for the 2011 period based on filed tax returns, resulting in a $39 million increase to additional paid-in capital. We are continuously undergoing examination of our income tax returns, which have been completed for our U.S. federal and state income tax returns through the 2009 and 2003 tax years, respectively. We had $16 million of unrecognized tax benefits as of September 30, 2014. Pursuant to our tax sharing agreement with Marathon Oil, the unrecognized tax benefits related to pre-spinoff operations for which Marathon Oil was the taxpayer remain the responsibility of Marathon Oil and we have indemnified Marathon Oil accordingly. See Note 22 for indemnification information.

Income Taxes

9 Months Ended

Sep. 30, 2014

The combined federal, state and foreign income tax rate was 33 percent and 32 percent for the three months ended September 30, 2014 and 2013, respectively, and 34 percent for both the nine months ended September 30, 2014 and 2013. The effective tax rate for the three and nine months ended September 30, 2014 and 2013 is slightly less than the U.S. statutory rate of 35 percent primarily due to certain permanent benefit differences, including the domestic manufacturing deduction, partially offset by state and local tax expense.

Prior to the June 30, 2011 spinoff transaction from Marathon Oil Corporation (“Marathon Oil”), we were included in Marathon Oil’s income tax returns for all applicable years. During 2011, we anticipated a future settlement between Marathon Oil and us upon the filing of Marathon Oil’s consolidated U.S. federal and state income tax returns for the period prior to June 30, 2011. During the second quarter of 2013, we settled with Marathon Oil for the 2011 period based on filed tax returns, resulting in a $39 million increase to additional paid-in capital.

We are continuously undergoing examination of our income tax returns, which have been completed for our U.S. federal and state income tax returns through the 2009 and 2003 tax years, respectively. We had $16 million of unrecognized tax benefits as of September 30, 2014. Pursuant to our tax sharing agreement with Marathon Oil, the unrecognized tax benefits related to pre-spinoff operations for which Marathon Oil was the taxpayer remain the responsibility of Marathon Oil and we have indemnified Marathon Oil accordingly. See Note 22 for indemnification information.