Income Taxes	3 Months Ended
Mar. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The combined federal, state and foreign income tax rate was 29 percent and (17) percent for the three months ended March 31, 2017 and 2016, respectively. The effective tax rate for the three months ended March 31, 2017 was less than the U.S. statutory rate of 35 percent primarily due to certain permanent tax differences related to equity compensation, net income attributable to noncontrolling interests and the domestic manufacturing deduction offset by state and local tax expense. The effective tax rate for the three months ended March 31, 2016 was significantly affected by permanent tax differences related to the net loss attributable to noncontrolling interest, including their proportional share of the goodwill impairment charge recorded by MPLX. The net loss attributable to noncontrolling interest reduced the effective rate for the three months ended March 31, 2016 by 51 percent from the U.S. statutory rate of 35 percent. 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 2007 tax years, respectively. We had $10 million of unrecognized tax benefits as of March 31, 2017. Pursuant to our tax sharing agreement with Marathon Oil Corporation (“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 21 for indemnification information.

Income Taxes

3 Months Ended

Mar. 31, 2017

The combined federal, state and foreign income tax rate was 29 percent and (17) percent for the three months ended March 31, 2017 and 2016, respectively. The effective tax rate for the three months ended March 31, 2017 was less than the U.S. statutory rate of 35 percent primarily due to certain permanent tax differences related to equity compensation, net income attributable to noncontrolling interests and the domestic manufacturing deduction offset by state and local tax expense. The effective tax rate for the three months ended March 31, 2016 was significantly affected by permanent tax differences related to the net loss attributable to noncontrolling interest, including their proportional share of the goodwill impairment charge recorded by MPLX. The net loss attributable to noncontrolling interest reduced the effective rate for the three months ended March 31, 2016 by 51 percent from the U.S. statutory rate of 35 percent.

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 2007 tax years, respectively. We had $10 million of unrecognized tax benefits as of March 31, 2017. Pursuant to our tax sharing agreement with Marathon Oil Corporation (“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 21 for indemnification information.