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
Issuance of common stock upon vesting of PSUs, shares		19,000
Net income (loss)	(1,388)
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
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
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
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)	$ (129,321)
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	259,778,494	259,778,000
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	259,778,494	259,778,000