Income Taxes (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax [Line Items]
Period of Average Annual Book Income Before Taxes	3 years
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	$ 21,638	$ 21,599
Federal statutory tax rate	35.00%	35.00%	35.00%
Unrecognized tax benefits, Increase (Decrease) resulting from tax positions taken in prior and current period tax returns.	500	1,400
Unrecognized tax benefits that would impact effective tax rate	2,500
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	600	1,600	2,200
Unrecognized tax benefits, interest on income taxes expense / (benefits)	200	(300)	200
Unrecognized tax benefits, income tax penalties and interest accrued	400	100
Internal Revenue Service (IRS)
Income Tax [Line Items]
Unrecognized Tax Benefits Resulting in Net Operating Loss Carryforward	17,300
Tax Year Closed	2009
State and Local Jurisdiction
Income Tax [Line Items]
Unrecognized Tax Benefits Resulting in Net Operating Loss Carryforward	400
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	1,800
NEW MEXICO
Income Tax [Line Items]
Tax Year Closed	2009
Minimum | Internal Revenue Service (IRS)
Income Tax [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2031
Minimum | State and Local Jurisdiction
Income Tax [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2016
Minimum | TEXAS
Income Tax [Line Items]
Income Tax Examination, Year under Examination	2007
Minimum | Year 1998 through year 2003 | ARIZONA
Income Tax [Line Items]
Open Tax Year	1998
Minimum | Year 2006 through year 2007 | ARIZONA
Income Tax [Line Items]
Open Tax Year	2006
Maximum | Internal Revenue Service (IRS)
Income Tax [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2033
Maximum | State and Local Jurisdiction
Income Tax [Line Items]
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2018
Maximum | TEXAS
Income Tax [Line Items]
Income Tax Examination, Year under Examination	2011
Maximum | Year 1998 through year 2003 | ARIZONA
Income Tax [Line Items]
Open Tax Year	2003
Maximum | Year 2006 through year 2007 | ARIZONA
Income Tax [Line Items]
Open Tax Year	2007
Change in Accounting Method Accounted for as Change in Estimate
Income Tax [Line Items]
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	4,500
Tax credit taken | ARIZONA
Income Tax [Line Items]
Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities	400
Unrecognized tax position of prior years recorded, net of decrease	$ 1,300