Income Taxes (Notes)	3 Months Ended
Income Taxes (Notes)	Mar. 31, 2014
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	Income Taxes We provide for income taxes for each interim period based on the estimated annual effective tax rate for the year, adjusting for discrete items in the quarter in which they arise. The annual effective tax rate before discrete items was 39.1% and 37.4% for the three-months ended March 31, 2014 and 2013, respectively. The 2014 annual effective tax rate differed from the statutory rate of 35% primarily due to the unfavorable impact of state income taxes, non-deductible equity charges, and other non-deductible expenditures, which were partially offset by the domestic production activities deduction. The 2013 annual effective tax rate differed from the statutory rate of 35% primarily due to the unfavorable impact of state income taxes, non-deductible equity charges, and other non-deductible expenditures, which were partially offset by the federal research and development credit claimed and the domestic production activities deduction. The income tax provision for the three months ended March 31, 2013 also reflected a discrete net benefit of $0.7 million, or 18.0% of pre-tax income, related to 2012 federal research and development credit which was retroactively reinstated in the three months ended March 31, 2013.

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

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