Income Tax	12 Months Ended
Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	18. Income Taxes We are not a taxable entity for United States federal income tax purposes or for the majority of states that impose an income tax. Taxes on our net income generally are borne by our partners through the allocation of taxable income. The aggregate difference in the basis of our net assets for financial and tax reporting purposes cannot be readily determined as we do not have access to information about each partner’s tax attributes in us. Our income tax expense results from state laws that apply to entities organized as partnerships, primarily in the state of Texas. Prior to the Offering, we had no taxable operations in the state of Texas. After the Offering, our income tax expense was $0.5 million and $0.1 million for the periods ended December 31, 2014 and 2013, respectively. Our effective tax rate for the periods ended December 31, 2014 and 2013 was 0.6% and 0.2%, respectively. As of December 31, 2014 and 2013, we had no unrecognized tax benefit liability. No interest or penalties were recognized related to income taxes during the years ended December 31, 2014, 2013 and 2012.

Income Tax

12 Months Ended

Dec. 31, 2014

18. Income Taxes

We are not a taxable entity for United States federal income tax purposes or for the majority of states that impose an income tax. Taxes on our net income generally are borne by our partners through the allocation of taxable income. The aggregate difference in the basis of our net assets for financial and tax reporting purposes cannot be readily determined as we do not have access to information about each partner’s tax attributes in us. Our income tax expense results from state laws that apply to entities organized as partnerships, primarily in the state of Texas. Prior to the Offering, we had no taxable operations in the state of Texas. After the Offering, our income tax expense was $0.5 million and $0.1 million for the periods ended December 31, 2014 and 2013, respectively. Our effective tax rate for the periods ended December 31, 2014 and 2013 was 0.6% and 0.2%, respectively.

As of December 31, 2014 and 2013, we had no unrecognized tax benefit liability. No interest or penalties were recognized related to income taxes during the years ended December 31, 2014, 2013 and 2012.