Income Taxes (Components of Deferred Tax Assets and Liabilities) (Details 2) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets
Loss and tax credit carryforwards - state	$ 52,917	$ 52,366
Business interest expense carryforward	24,513	9,049
Business credit carryforwards	71,555	79,528
Unrecognized gain and original issue discount on debt exchange	41,556	73,937
Accrued liabilities and other reserves	29,788	25,231
Other	18,725	23,208
Valuation allowances	(77,215)	(51,093)	$ (51,134)	$ (36,510)
Total deferred tax assets	161,839	212,226
Deferred tax liabilities
Property and equipment	(569,254)	(492,214)
Derivative contracts	(1,120)	(23,127)
Other	(1,695)	(6,643)
Total deferred tax liabilities	(572,069)	(521,984)
Total net deferred tax liability	$ (410,230)	$ (309,758)