Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Gains (Losses) [Member]	Treasury Stock [Member]
Beginning Balance at Dec. 31, 2018	$ 3,584,653	$ 1,444	$ 2,018,143	$ 1,769,415	$ 21	$ (204,370)
Beginning Balance, shares at Dec. 31, 2018		144,383,662				6,945,309
Net loss	(187,316)			(187,316)
Stock-based compensation, net of tax	1,587	$ 4	2,952			$ (1,369)
Stock-based compensation, net of tax, shares		380,463				128,189
Net loss on investments	(24)				(24)
Net loss on derivative financial instruments	(3)				(3)
Ending Balance at Jun. 30, 2019	3,398,897	$ 1,448	2,021,095	1,582,099	(6)	$ (205,739)
Ending Balance, shares at Jun. 30, 2019		144,764,125				7,073,498
Beginning Balance at Mar. 31, 2019	3,511,876	$ 1,446	2,019,555	1,696,087	2	$ (205,214)
Beginning Balance, shares at Mar. 31, 2019		144,606,992				7,026,789
Net loss	(113,988)			(113,988)
Stock-based compensation, net of tax	1,017	$ 2	1,540			$ (525)
Stock-based compensation, net of tax, shares		157,133				46,709
Net loss on investments	(6)				(6)
Net loss on derivative financial instruments	(2)				(2)
Ending Balance at Jun. 30, 2019	3,398,897	$ 1,448	2,021,095	1,582,099	(6)	$ (205,739)
Ending Balance, shares at Jun. 30, 2019		144,764,125				7,073,498
Beginning Balance at Dec. 31, 2019	3,232,210	$ 1,448	2,024,347	1,412,201	(18)	$ (205,768)
Beginning Balance, shares at Dec. 31, 2019		144,781,766				7,077,856
Net loss	(1,006,760)			(1,006,760)
Stock-based compensation, net of tax	5,242	$ 5	5,631			$ (394)
Stock-based compensation, net of tax, shares		476,770				130,333
Net loss on derivative financial instruments	(3)				(3)
Ending Balance at Jun. 30, 2020	2,230,689	$ 1,453	2,029,978	405,441	(21)	$ (206,162)
Ending Balance, shares at Jun. 30, 2020		145,258,536				7,208,189
Beginning Balance at Mar. 31, 2020	2,371,488	$ 1,451	2,025,887	550,261	(19)	$ (206,092)
Beginning Balance, shares at Mar. 31, 2020		145,107,046				7,162,987
Net loss	(144,820)			(144,820)
Stock-based compensation, net of tax	4,023	$ 2	4,091			$ (70)
Stock-based compensation, net of tax, shares		151,490				45,202
Net loss on derivative financial instruments	(2)				(2)
Ending Balance at Jun. 30, 2020	$ 2,230,689	$ 1,453	$ 2,029,978	$ 405,441	$ (21)	$ (206,162)
Ending Balance, shares at Jun. 30, 2020		145,258,536				7,208,189