CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Treasury Stock	Noncontrolling Interest	Total
Balance at Dec. 31, 2019	$ 1,013	$ 1,258,859	$ 27	$ (946,404)		$ 28,621	$ 342,116
Balance (in shares) at Dec. 31, 2019	101,288
Increase (Decrease) in Stockholders' Equity
Distributions to noncontrolling interest	$ 0	0	0	0		(15,810)	(15,810)
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding	$ 0	170	0	0		0	170
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding (in shares)	32
Stock-based compensation	$ 0	435	0	0		0	435
Net income	0	0	0	65,437		13,515	78,952
Other comprehensive income	0	0	6	0		0	6
Balance at Mar. 31, 2020	$ 1,013	1,259,464	33	(880,967)		26,326	405,869
Balance (in shares) at Mar. 31, 2020	101,320
Balance at Dec. 31, 2019	$ 1,013	1,258,859	27	(946,404)		28,621	342,116
Balance (in shares) at Dec. 31, 2019	101,288
Increase (Decrease) in Stockholders' Equity
Net income							177,177
Balance at Jun. 30, 2020	$ 1,015	1,260,017	(2)	(804,123)		35,905	492,812
Balance (in shares) at Jun. 30, 2020	101,392
Balance at Mar. 31, 2020	$ 1,013	1,259,464	33	(880,967)		26,326	405,869
Balance (in shares) at Mar. 31, 2020	101,320
Increase (Decrease) in Stockholders' Equity
Distributions to noncontrolling interest	$ 0	0	0	0		(12,152)	(12,152)
Equity activity of noncontrolling interest from a consolidated variable interest entity	0	0	0	0		350	350
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding	$ 2	178	0	0		0	180
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding (in shares)	72
Stock-based compensation	$ 0	375	0	0		0	375
Net income	0	0	0	76,844		21,381	98,225
Other comprehensive income	0	0	(35)	0		0	(35)
Balance at Jun. 30, 2020	$ 1,015	1,260,017	(2)	(804,123)		35,905	492,812
Balance (in shares) at Jun. 30, 2020	101,392
Balance at Dec. 31, 2020	$ 1,014	1,260,900	0	(722,002)	$ 0	67,925	$ 607,837	[1]
Balance (in shares) at Dec. 31, 2020	101,392						101,392
Increase (Decrease) in Stockholders' Equity
Distributions to noncontrolling interest	$ 0	0	0	0	0	(21,285)	$ (21,285)
Equity activity of noncontrolling interest from a consolidated variable interest entity	0	0	0	0	0	8	8
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding	$ 0	(25)	0	0	0	0	(25)
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding (in shares)	16
Stock-based compensation	$ 0	451	0	0	0	0	451
Net income	0	0	0	94,123	0	15,572	109,695
Balance at Mar. 31, 2021	$ 1,014	1,261,326	0	(627,879)	0	62,220	696,681
Balance (in shares) at Mar. 31, 2021	101,408
Balance at Dec. 31, 2020	$ 1,014	1,260,900	0	(722,002)	0	67,925	$ 607,837	[1]
Balance (in shares) at Dec. 31, 2020	101,392						101,392
Increase (Decrease) in Stockholders' Equity
Net income							$ 220,541
Balance at Jun. 30, 2021	$ 695	1,261,845	0	(538,931)	$ (393,829)	63,965	$ 393,745
Balance (in shares) at Jun. 30, 2021	69,495				32,005		69,495
Balance at Mar. 31, 2021	$ 1,014	1,261,326	0	(627,879)	$ 0	62,220	$ 696,681
Balance (in shares) at Mar. 31, 2021	101,408
Increase (Decrease) in Stockholders' Equity
Distributions to noncontrolling interest	$ 0	0	0	0	0	(20,161)	(20,161)
Equity activity of noncontrolling interest from a consolidated variable interest entity	0	0	0	0	0	8	8
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding	$ 1	49	0	0	0	0	50
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding (in shares)	92
Repurchase of common stock	$ (320)	0	0	0	$ (393,829)	0	(394,149)
Repurchase of common stock (in shares)	(32,005)				32,005
Stock-based compensation	$ 0	470	0	0	$ 0	0	470
Net income	0	0	0	88,948	0	21,898	110,846
Balance at Jun. 30, 2021	$ 695	$ 1,261,845	$ 0	$ (538,931)	$ (393,829)	$ 63,965	$ 393,745
Balance (in shares) at Jun. 30, 2021	69,495				32,005		69,495

[1] Consolidated balance sheet as of December 31, 2020 has been derived from audited consolidated financial statements.