Condensed Consolidated Statements of Shareholders' Equity Statement (unaudited) - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-In-Capital	Treasury Stock	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2018	$ 1,928,504	$ (5,549)	$ 7	$ 371,225	$ (67,016)	$ 1,625,481	$ (5,549)	$ (1,193)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	3,671			3,671
Repurchase of common stock	(5,223)				(5,223)
Proceeds from options exercised	0
Changes in comprehensive income	177							177
Net income (loss)	56,076					56,076
Ending balance at Mar. 31, 2019	1,977,656		7	374,896	(72,239)	1,676,008		(1,016)
Beginning balance at Dec. 31, 2018	1,928,504	(5,549)	7	371,225	(67,016)	1,625,481	(5,549)	(1,193)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Changes in comprehensive income	318
Net income (loss)	254,041
Ending balance at Sep. 30, 2019	$ 2,180,087		7	379,354	(72,372)	1,873,973		(875)
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Beginning balance at Dec. 31, 2018	$ 1,928,504	(5,549)	7	371,225	(67,016)	1,625,481	(5,549)	(1,193)
Ending balance at Dec. 31, 2019	2,261,332	(1,609)	7	379,380	(72,455)	1,955,187	(1,609)	(787)
Beginning balance at Mar. 31, 2019	1,977,656		7	374,896	(72,239)	1,676,008		(1,016)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	2,742			2,742
Repurchase of common stock	(25)				(25)
Proceeds from options exercised	1			1
Changes in comprehensive income	152							152
Net income (loss)	114,501					114,501
Ending balance at Jun. 30, 2019	2,095,027		7	377,639	(72,264)	1,790,509		(864)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	1,715			1,715
Repurchase of common stock	(108)				(108)
Proceeds from options exercised	0			0
Changes in comprehensive income	(11)							(11)
Net income (loss)	83,464					83,464
Ending balance at Sep. 30, 2019	2,180,087		7	379,354	(72,372)	1,873,973		(875)
Beginning balance at Dec. 31, 2019	2,261,332	(1,609)	7	379,380	(72,455)	1,955,187	(1,609)	(787)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	3,790			3,790
Repurchase of common stock	(1,536)				(1,536)
Proceeds from options exercised	16			16
Changes in comprehensive income	226							226
Net income (loss)	(27,828)					(27,828)
Ending balance at Mar. 31, 2020	$ 2,234,391		7	383,186	(73,991)	1,925,750		(561)
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Beginning balance at Dec. 31, 2019	$ 2,261,332	$ (1,609)	7	379,380	(72,455)	1,955,187	$ (1,609)	(787)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Changes in comprehensive income	179
Net income (loss)	(271,396)
Ending balance at Sep. 30, 2020	2,404,103		28	796,553	(74,052)	1,682,182		(608)
Beginning balance at Mar. 31, 2020	2,234,391		7	383,186	(73,991)	1,925,750		(561)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock and warrants, net	194,886		20	194,866
Equity component value of convertible debt issuance, net	55,590			55,590
Share-based compensation	2,652			2,652
Repurchase of common stock	(18)				(18)
Proceeds from options exercised	23			23
Changes in comprehensive income	66							66
Net income (loss)	(144,428)					(144,428)
Ending balance at Jun. 30, 2020	2,343,162		27	636,317	(74,009)	1,781,322		(495)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock and warrants, net	158,083		1	158,082
Share-based compensation	2,154			2,154
Repurchase of common stock	(43)				(43)
Proceeds from options exercised	0			0
Changes in comprehensive income	(113)							(113)
Net income (loss)	(99,140)					(99,140)
Ending balance at Sep. 30, 2020	$ 2,404,103		$ 28	$ 796,553	$ (74,052)	$ 1,682,182		$ (608)