CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Common stock held in treasury	Additional paid-in capital	Retained deficit	Accumulated other comprehensive loss
Beginning balance at Dec. 31, 2019	$ 2,347,488	$ 2,514	$ (7,236)	$ 5,659,832	$ (3,306,834)	$ (788)
Beginning balance Shares at Dec. 31, 2019		251,439,000
Issuance of common stock	(1,364)	$ 42	0	(1,406)	0	0
Issuance of common stock, shares		4,246,000
Stock-based compensation expense	5,963	$ 0	0	5,963	0	0
Treasury stock	(22,547)	0	(22,514)	(33)	0	0
Other comprehensive income	73	0	0	0	0	73
Net income (loss)	166,195	0	0	0	166,195	0
Ending balance at Mar. 31, 2020	2,495,808	$ 2,556	(29,750)	5,664,356	(3,140,639)	(715)
Ending balance Shares at Mar. 31, 2020		255,685,000
Beginning balance at Dec. 31, 2019	2,347,488	$ 2,514	(7,236)	5,659,832	(3,306,834)	(788)
Beginning balance Shares at Dec. 31, 2019		251,439,000
Net income (loss)	(750,178)
Ending balance at Sep. 30, 2020	1,593,968	$ 2,562	(30,131)	5,679,197	(4,057,086)	(574)
Ending balance Shares at Sep. 30, 2020		256,232,000
Beginning balance at Dec. 31, 2019	2,347,488	$ 2,514	(7,236)	5,659,832	(3,306,834)	(788)
Beginning balance Shares at Dec. 31, 2019		251,439,000
Ending balance at Dec. 31, 2020	$ 1,637,535	$ 2,563	(30,132)	5,684,268	(4,018,685)	(479)
Ending balance Shares at Dec. 31, 2020	256,353,887	256,354,000
Beginning balance at Mar. 31, 2020	$ 2,495,808	$ 2,556	(29,750)	5,664,356	(3,140,639)	(715)
Beginning balance Shares at Mar. 31, 2020		255,685,000
Issuance of common stock	858	$ 4	0	854	0	0
Issuance of common stock, shares		376,000
Issuance of common stock upon vesting of PSUs	0	$ 0	0	74	(74)	0
Issuance of common stock upon vesting of PSUs, shares		19,000
Stock-based compensation expense	7,312	$ 0	0	7,312	0	0
Treasury stock	(444)	0	(444)	0	0	0
Other comprehensive income	71	0	0	0	0	71
Net income (loss)	(167,583)	0	0	0	(167,583)	0
Ending balance at Jun. 30, 2020	2,336,022	$ 2,560	(30,194)	5,672,596	(3,308,296)	(644)
Ending balance Shares at Jun. 30, 2020		256,080,000
Issuance of common stock	75	$ 2	0	73	0	0
Issuance of common stock, shares		152,000
Stock-based compensation expense	6,591	$ 0	0	6,591	0	0
Treasury stock	0	0	63	(63)	0	0
Other comprehensive income	70	0	0	0	0	70
Net income (loss)	(748,790)	0	0	0	(748,790)	0
Ending balance at Sep. 30, 2020	1,593,968	$ 2,562	(30,131)	5,679,197	(4,057,086)	(574)
Ending balance Shares at Sep. 30, 2020		256,232,000
Beginning balance at Dec. 31, 2020	$ 1,637,535	$ 2,563	(30,132)	5,684,268	(4,018,685)	(479)
Beginning balance Shares at Dec. 31, 2020	256,353,887	256,354,000
Issuance of common stock	$ (7,621)	$ 33	0	(7,654)	0	0
Issuance of common stock, shares		3,218,000
Issuance of common stock upon vesting of PSUs	0	$ 0	0	148	(148)	0
Stock-based compensation expense	6,713	0	0	6,713	0	0
Treasury stock	0	0	47	(47)	0	0
Other comprehensive income	70	0	0	0	0	70
Net income (loss)	27,151	0	0	0	27,151	0
Ending balance at Mar. 31, 2021	1,663,848	$ 2,596	(30,085)	5,683,428	(3,991,682)	(409)
Ending balance Shares at Mar. 31, 2021		259,572,000
Beginning balance at Dec. 31, 2020	$ 1,637,535	$ 2,563	(30,132)	5,684,268	(4,018,685)	(479)
Beginning balance Shares at Dec. 31, 2020	256,353,887	256,354,000
Net income (loss)	$ (479,588)
Ending balance at Sep. 30, 2021	$ 1,181,284	$ 2,598	(30,007)	5,707,382	(4,498,421)	(268)
Ending balance Shares at Sep. 30, 2021	259,787,004	259,787,000
Beginning balance at Mar. 31, 2021	$ 1,663,848	$ 2,596	(30,085)	5,683,428	(3,991,682)	(409)
Beginning balance Shares at Mar. 31, 2021		259,572,000
Issuance of common stock	9,291	$ 2	0	9,289	0	0
Issuance of common stock, shares		206,000
Stock-based compensation expense	6,523	$ 0	0	6,523	0	0
Treasury stock	0	0	0	0	0	0
Other comprehensive income	71	0	0	0	0	71
Net income (loss)	(156,472)	0	0	0	(156,472)	0
Ending balance at Jun. 30, 2021	1,523,261	$ 2,598	(30,085)	5,699,240	(4,148,154)	(338)
Ending balance Shares at Jun. 30, 2021		259,778,000
Issuance of common stock	754	$ 0	0	754	0	0
Issuance of common stock, shares		9,000
Stock-based compensation expense	7,466	$ 0	0	7,466	0	0
Treasury stock	0	0	78	78	0	0
Other comprehensive income	70	0	0	0	0	70
Net income (loss)	(350,267)	0	0	0	(350,267)	0
Ending balance at Sep. 30, 2021	$ 1,181,284	$ 2,598	$ (30,007)	$ 5,707,382	$ (4,498,421)	$ (268)
Ending balance Shares at Sep. 30, 2021	259,787,004	259,787,000