Income Taxes (Components of Deferred Tax Assets and Liabilities) (Details 1) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets
Loss carryforwards - federal	$ 0	$ 18,581
Loss and tax credit carryforwards - state	52,366	53,367
Tax credit carryover	0	20,270
Business credit carryforwards	79,528	73,057
Derivative contracts	0	23,024
Unrecognized gain and original issue discount on debt exchange	73,937	85,951
Accrued liabilities and other reserves	25,231	2,673
Other	32,257	29,681
Valuation allowance	(51,093)	(51,134)
Total deferred tax assets	212,226	255,470
Deferred tax liabilities
Property and equipment	(492,214)	(450,629)
Derivative contracts	(23,127)	0
Other	(6,643)	(2,940)
Total deferred tax liabilities	(521,984)	(453,569)
Total net deferred tax liability	$ (309,758)	$ (198,099)