INCOME TAXES Tax Effects of Temporary differences that Give Rise to Significant Portions of the Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Components of Deferred Tax Assets [Abstract]
Deferred compensation	$ 6,059	$ 9,338
Asset retirement obligations	21,760	34,359
deferred tax assets, federal tax	19,386	29,988
State NOL and tax credit carryforwards, net	7,815	5,189
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	4,366	5,184
Deferred tax assets, Allowance for note receivable	0	17,292
Deferred Tax Assets, Derivative Instruments	20,929	26,262
Other	2,453	4,716
Deferred tax assets	82,768	132,328
Components of Deferred Tax Liabilities [Abstract]
properties and equipment	267,498	518,964
Convertible debt	7,262	14,231
Total gross deferred tax liabilities	274,760	533,195
Net deferred tax liability	$ 191,992	$ 400,867