Income Taxes (Details) - USD ($) $ in Thousands		12 Months Ended
	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax [Line Items]
Period of Average Annual Book Income Before Taxes		3 years
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax		$ 16,620	$ 16,620
Federal statutory tax rate		35.00%	35.00%	35.00%
Deferred Income Tax Expense (Benefit)		$ 50,510	$ 30,846	$ 39,129
Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions		0	0	0
Unrecognized tax benefits, Increase (Decrease) resulting from tax positions taken in prior and current period tax returns.		(400)	(800)	(2,100)
Unrecognized Tax Benefits, Increase Resulting from Settlements with Taxing Authorities		500
Unrecognized tax benefits that would impact effective tax rate		2,600
Unrecognized tax benefits, interest on income taxes expense (benefit)		100	200	100
Unrecognized tax benefits, income tax penalties and interest accrued		800	700
Unrecognized Tax Benefits		5,300	$ 6,000	5,200	$ 7,200
Internal Revenue Service (IRS)
Income Tax [Line Items]
Tax Credit Carryforward, Amount		$ 59,300
Live Of Tax Loss Carrforwards		20 years
State and Local Jurisdiction
Income Tax [Line Items]
Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions		$ 700
Tax Credit Carryforward, Amount		$ 2,200
Live Of Tax Loss Carrforwards		5 years
Tax credit taken | ARIZONA
Income Tax [Line Items]
Increase (Decrease) in Unrecognized Tax Position of Prior Years Recorded, net		$ (300)		(1,300)
Unrecognized Tax Benefits, Increase Resulting from Settlements with Taxing Authorities				$ 400
Earliest Tax Year | TEXAS
Income Tax [Line Items]
Income Tax Examination, Year under Examination		2007
Earliest Tax Year | ARIZONA
Income Tax [Line Items]
Tax Year Closed	2009
Latest Tax Year | Internal Revenue Service (IRS)
Income Tax [Line Items]
Tax Year Closed		2011
Latest Tax Year | NEW MEXICO
Income Tax [Line Items]
Tax Year Closed		2011
Latest Tax Year | TEXAS
Income Tax [Line Items]
Income Tax Examination, Year under Examination		2011
Latest Tax Year | ARIZONA
Income Tax [Line Items]
Tax Year Closed	2012
Change in Accounting Method Accounted for as Change in Estimate [Member]
Income Tax [Line Items]
Deferred Income Tax Expense (Benefit)		$ 5,100
Stock Compensation Plan
Income Tax [Line Items]
Unrecognized Tax Benefits		200
Accounting Standards Update 2015-17 [Member]
Income Tax [Line Items]
Prior Period Reclassification Adjustment		$ 21,600