8.  Income Taxes  

Our income tax benefit for the three and nine months ended September 30, 2015 was $18.5 million and $166.2 million, respectively.  Our effective tax rate for the three and nine months ended September 30, 2015 was 3.7% and 14.3%, respectively.  Both of these percentages differ from the federal statutory rate of 35.0% primarily due to recording a valuation allowance for our deferred tax assets.  Income tax expense for the three and nine months ended September 30, 2014 was $0.9 million and $12.8 million, respectively.  Our effective tax rate for the three months ended September 30, 2014 was not meaningful due to adjustments for a revised estimated effective rate computed on a year-to-date basis.  Our effective tax rate for the nine months ended September 30, 2014 was 37.1%, and differed from the federal statutory rate primarily as a result of state income taxes and other permanent items.  

 During the three and nine months ended September 30, 2015, we recorded a valuation allowance of $156.2 million and $241.6 million, respectively, related to federal and state deferred tax assets. Deferred tax assets are recorded related to net operating losses and temporary differences between the book and tax basis of assets and liabilities expected to produce tax deductions in future periods.  The realization of these assets depends on recognition of sufficient future taxable income in specific tax jurisdictions in which those temporary differences or net operating losses are deductible.  In assessing the need for a valuation allowance on our deferred tax assets, we consider whether it is more likely than not that some portion or all of them will not be realized.  Additionally, as of September 30, 2015 and December 31, 2014, we had a valuation allowance related to Louisiana state net operating losses of $4.3 million for both periods.  The tax years 2012 through 2014 remain open to examination for Federal purposes.  The tax years from 2011 through 2014 remain open to examination by some of the state tax jurisdictions to which we are subject.  

We recognize interest and penalties related to unrecognized tax benefits in income tax expense.  During the nine months ended September 30, 2015 and 2014, we recorded immaterial amounts of accrued interest expense related to our unrecognized tax benefit.