Income Taxes	6 Months Ended
Jun. 30, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The effective income tax rate, which is the provision for income taxes as a percentage of income before provision for income taxes and equity income, was 31.6% and 38.2% for the three months ended June 30, 2015 and 2014, respectively. The effective income tax rate was 33.2% and 37.0% for the six months ended June 30, 2015 and 2014, respectively. The effective tax rates for the three and six months ended June 30, 2015 and 2014 differed from the U.S. Federal statutory rate of 35% primarily due to state income taxes, utilization of foreign tax credits in 2015 due to the sale of our share of the Dowa Joint Venture, the domestic manufacturing deduction, and discrete tax items that impacted the provision for income taxes in these periods. As of June 30, 2015, December 31, 2014 and June 30, 2014, we had $25.2 million, $25.2 million and $25.7 million, respectively, of unrecognized tax benefits, none of which would impact the effective tax rate, if recognized. Estimated interest and penalties related to the underpayment of income taxes are classified as a component of provision for income taxes. There were no such estimated amounts for the three and six months ended June 30, 2015 or June 30, 2014. Accrued interest and penalties as of June 30, 2015, December 31, 2014 and June 30, 2014 was $0.1 million. Our liability for uncertain tax positions of $25.3 million, $25.3 million and $25.8 million at June 30, 2015, December 31, 2014 and June 30, 2014, respectively, is presented in other noncurrent liabilities in the accompanying unaudited consolidated balance sheets. Our U.S. federal returns for the period ended December 31, 2011 and all subsequent periods remain open for audit. The majority of state returns for the period ended December 31, 2010 and all subsequent periods remain open for audit.

Income Taxes

6 Months Ended

Jun. 30, 2015

The effective income tax rate, which is the provision for income taxes as a percentage of income before provision for income taxes and equity income, was 31.6% and 38.2% for the three months ended June 30, 2015 and 2014, respectively. The effective income tax rate was 33.2% and 37.0% for the six months ended June 30, 2015 and 2014, respectively. The effective tax rates for the three and six months ended June 30, 2015 and 2014 differed from the U.S. Federal statutory rate of 35% primarily due to state income taxes, utilization of foreign tax credits in 2015 due to the sale of our share of the Dowa Joint Venture, the domestic manufacturing deduction, and discrete tax items that impacted the provision for income taxes in these periods.

As of June 30, 2015, December 31, 2014 and June 30, 2014, we had $25.2 million, $25.2 million and $25.7 million, respectively, of unrecognized tax benefits, none of which would impact the effective tax rate, if recognized. Estimated interest and penalties related to the underpayment of income taxes are classified as a component of provision for income taxes. There were no such estimated amounts for the three and six months ended June 30, 2015 or June 30, 2014. Accrued interest and penalties as of June 30, 2015, December 31, 2014 and June 30, 2014 was $0.1 million. Our liability for uncertain tax positions of $25.3 million, $25.3 million and $25.8 million at June 30, 2015, December 31, 2014 and June 30, 2014, respectively, is presented in other noncurrent liabilities in the accompanying unaudited consolidated balance sheets.

Our U.S. federal returns for the period ended December 31, 2011 and all subsequent periods remain open for audit. The majority of state returns for the period ended December 31, 2010 and all subsequent periods remain open for audit.