Consolidated Statements of Stockholders' Equity - 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, 2016	$ 3,750,134	$ 1,440	$ 2,004,514	$ 1,946,765	$ 1	$ (202,586)
Beginning Balance, shares at Dec. 31, 2016		143,997,757				6,828,094
Impact of change in accounting principle at Dec. 31, 2016			634	(634)
Adjusted balance at Dec. 31, 2016	3,750,134	$ 1,440	2,005,148	1,946,131	1	$ (202,586)
Adjusted balance, shares at Dec. 31, 2016		143,997,757				6,828,094
Net (loss) income	18,346			18,346
Anti-dilution adjustment	20			20
Stock-based compensation, net of tax	5,767	$ 1	6,249			$ (483)
Stock-based compensation, net of tax, shares		87,535				29,416
Net loss on derivative financial instruments	(6)				(6)
Ending Balance at Dec. 31, 2017	3,774,261	$ 1,441	2,011,397	1,964,497	(5)	$ (203,069)
Ending Balance, shares at Dec. 31, 2017		144,085,292				6,857,510
Impact of change in accounting principle at Dec. 31, 2017	(14,812)			(14,812)
Adjusted balance at Dec. 31, 2017	3,759,449	$ 1,441	2,011,397	1,949,685	(5)	$ (203,069)
Adjusted balance, shares at Dec. 31, 2017		144,085,292				6,857,510
Net (loss) income	(180,272)			(180,272)
Anti-dilution adjustment	2			2
Stock options exercised, shares		3,773
Stock-based compensation, net of tax	5,448	$ 3	6,746			$ (1,301)
Stock-based compensation, net of tax, shares		294,597				87,799
Net loss on derivative financial instruments	(6)				(6)
Net gain (loss) on investments	32				32
Ending Balance at Dec. 31, 2018	3,584,653	$ 1,444	2,018,143	1,769,415	21	$ (204,370)
Ending Balance, shares at Dec. 31, 2018		144,383,662				6,945,309
Net (loss) income	(357,214)			(357,214)
Stock-based compensation, net of tax	4,810	$ 4	6,204			$ (1,398)
Stock-based compensation, net of tax, shares		398,104				132,547
Net loss on derivative financial instruments	(7)				(7)
Net gain (loss) on investments	(32)				(32)
Ending Balance at Dec. 31, 2019	$ 3,232,210	$ 1,448	$ 2,024,347	$ 1,412,201	$ (18)	$ (205,768)
Ending Balance, shares at Dec. 31, 2019		144,781,766				7,077,856