Income Taxes	6 Months Ended
Jun. 30, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes. In accordance with FASB ASC Topic 740, Income Taxes, we analyze all positive and negative evidence and maintain a valuation allowance on deferred tax assets that are not considered more likely than not to be realized. Based on current analysis, including increased level of income and ability to use losses previously limited, we have determined that it is more likely than not that a significant portion of our U.S. tax loss carryforwards and credits will be realized and have released the valuation allowance on these deferred tax assets. For the three months ended June 30, 2017, we recorded an income tax expense of $16 million on pre-tax income of approximately $1.7 billion compared to an income tax expense of $50 million on pre-tax loss of $235 million for the three months ended June 30, 2016. Our effective income tax rate was 0.9% and (21.3)% for the three months ended June 30, 2017 and 2016, respectively. For the three months ended June 30, 2017, the effective tax rate was lower than the statutory federal rate of 35%, primarily due to a decrease in the valuation allowance and partnership income for which there was no tax expense, as such income is allocated to the partners. For the three months ended June 30, 2016, the effective tax rate was lower than the statutory federal rate of 35%, primarily due to partnership losses for which there was no tax benefit, as such losses are allocated to the partners. For the six months ended June 30, 2017, we recorded an income tax expense of $42 million on pre-tax income of approximately $1.6 billion compared to an income tax expense of $66 million on pre-tax loss of approximately $1.8 billion for the six months ended June 30, 2016. Our effective income tax rate was 2.6% and (3.6)% for the six months ended June 30, 2017 and 2016, respectively. For the six months ended June 30, 2017, the effective tax rate was lower than the statutory federal rate of 35%, primarily due to a decrease in the valuation allowance and partnership income for which there was no tax expense, as such income is allocated to the partners. For the six months ended June 30, 2016, the effective tax rate was lower than the statutory federal rate of 35%, primarily due to partnership losses for which there was no tax benefit, as such losses are allocated to the partners, and goodwill impairment not deductible for tax purposes.

Income Taxes.

In accordance with FASB ASC Topic 740, Income Taxes, we analyze all positive and negative evidence and maintain a valuation allowance on deferred tax assets that are not considered more likely than not to be realized. Based on current analysis, including increased level of income and ability to use losses previously limited, we have determined that it is more likely than not that a significant portion of our U.S. tax loss carryforwards and credits will be realized and have released the valuation allowance on these deferred tax assets.

For the three months ended June 30, 2017, we recorded an income tax expense of $16 million on pre-tax income of approximately $1.7 billion compared to an income tax expense of $50 million on pre-tax loss of $235 million for the three months ended June 30, 2016. Our effective income tax rate was 0.9% and (21.3)% for the three months ended June 30, 2017 and 2016, respectively.

For the three months ended June 30, 2017, the effective tax rate was lower than the statutory federal rate of 35%, primarily due to a decrease in the valuation allowance and partnership income for which there was no tax expense, as such income is allocated to the partners.

For the three months ended June 30, 2016, the effective tax rate was lower than the statutory federal rate of 35%, primarily due to partnership losses for which there was no tax benefit, as such losses are allocated to the partners.

For the six months ended June 30, 2017, we recorded an income tax expense of $42 million on pre-tax income of approximately $1.6 billion compared to an income tax expense of $66 million on pre-tax loss of approximately $1.8 billion for the six months ended June 30, 2016. Our effective income tax rate was 2.6% and (3.6)% for the six months ended June 30, 2017 and 2016, respectively.

For the six months ended June 30, 2017, the effective tax rate was lower than the statutory federal rate of 35%, primarily due to a decrease in the valuation allowance and partnership income for which there was no tax expense, as such income is allocated to the partners.

For the six months ended June 30, 2016, the effective tax rate was lower than the statutory federal rate of 35%, primarily due to partnership losses for which there was no tax benefit, as such losses are allocated to the partners, and goodwill impairment not deductible for tax purposes.