Income Taxes	6 Months Ended
Jun. 30, 2014
Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]
Income Taxes	Income Taxes The Company files income tax returns in the United States ("U.S.") federal jurisdiction and in the states of Texas, New Mexico and Arizona. The Company is no longer subject to tax examination by the taxing authorities in the federal and New Mexico jurisdictions for years prior to 2009 and in Arizona for years prior to 2008. The Company is currently under audit in Texas for tax years 2007 through 2011. The Company reached a settlement with the Arizona Department of Revenue in March 2014 in their audit of income tax returns for the years 1998 through 2007 which did not have a material effect on income tax expense. For the three months ended June 30, 2014 and 2013, the Company’s effective tax rate was 32.9% and 35.3%, respectively. For the six months ended June 30, 2014 and 2013, the Company's effective tax rate was 31.9% and 34.3%, respectively. For the twelve months ended June 30, 2014 and 2013, the Company's effective tax rate was 32.0% and 34.4%, respectively. The Company's effective tax rate for all time periods presented differs from the federal statutory tax rate of 35.0% primarily due to the allowance for equity funds used during construction and state income taxes. The Company's effective tax rate for the six months ended June 30, 2014 also differs from the federal statutory tax rate of 35.0% due to capital gains in the qualified decommissioning trusts realized in the first quarter of 2014, which are taxed at a federal rate of 20.0%.

Income Taxes

6 Months Ended

Jun. 30, 2014

Components of Income Tax Expense (Benefit), Continuing Operations [Abstract]

The Company files income tax returns in the United States ("U.S.") federal jurisdiction and in the states of Texas, New Mexico and Arizona. The Company is no longer subject to tax examination by the taxing authorities in the federal and New Mexico jurisdictions for years prior to 2009 and in Arizona for years prior to 2008. The Company is currently under audit in Texas for tax years 2007 through 2011. The Company reached a settlement with the Arizona Department of Revenue in March 2014 in their audit of income tax returns for the years 1998 through 2007 which did not have a material effect on income tax expense.

For the three months ended June 30, 2014 and 2013, the Company’s effective tax rate was 32.9% and 35.3%, respectively. For the six months ended June 30, 2014 and 2013, the Company's effective tax rate was 31.9% and 34.3%, respectively. For the twelve months ended June 30, 2014 and 2013, the Company's effective tax rate was 32.0% and 34.4%, respectively. The Company's effective tax rate for all time periods presented differs from the federal statutory tax rate of 35.0% primarily due to the allowance for equity funds used during construction and state income taxes. The Company's effective tax rate for the six months ended June 30, 2014 also differs from the federal statutory tax rate of 35.0% due to capital gains in the qualified decommissioning trusts realized in the first quarter of 2014, which are taxed at a federal rate of 20.0%.