CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total		Common stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Treasury Stock	Noncontrolling Interest
Balance at Dec. 31, 2019	$ 342,116		$ 1,013	$ 1,258,859	$ 27	$ (946,404)		$ 28,621
Balance (in shares) at Dec. 31, 2019			101,288,000
Increase (Decrease) in Stockholders' Equity
Distributions to noncontrolling interest	(15,810)		$ 0	0	0	0		(15,810)
Distributions to noncontrolling interest (in shares)			0
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding	170		$ 0	170	0	0		0
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding (in shares)			32,000
Stock-based compensation	435		$ 0	435	0	0		0
Stock-based compensation (in shares)			0
Net income	78,952		$ 0	0	0	65,437		13,515
Net income (in shares)			0
Other comprehensive income	6		$ 0	0	6	0		0
Other comprehensive income (in shares)			0
Balance at Mar. 31, 2020	405,869		$ 1,013	1,259,464	33	(880,967)		26,326
Balance (in shares) at Mar. 31, 2020			101,320,000
Balance at Dec. 31, 2019	342,116		$ 1,013	1,258,859	27	(946,404)		28,621
Balance (in shares) at Dec. 31, 2019			101,288,000
Increase (Decrease) in Stockholders' Equity
Net income	218,798
Balance at Sep. 30, 2020	534,872		$ 1,014	1,260,447	0	(775,905)		49,316
Balance (in shares) at Sep. 30, 2020			101,391,000
Balance at Mar. 31, 2020	405,869		$ 1,013	1,259,464	33	(880,967)		26,326
Balance (in shares) at Mar. 31, 2020			101,320,000
Increase (Decrease) in Stockholders' Equity
Distributions to noncontrolling interest	(12,152)		$ 0	0	0	0		(12,152)
Distributions to noncontrolling interest (in shares)			0
Equity activity of noncontrolling interest from a consolidated variable interest entity	350		$ 0	0	0	0		350
Equity activity of noncontrolling interest from a consolidated variable interest entity (in shares)			0
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding	180		$ 2	178	0	0		0
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding (in shares)			72,000
Stock-based compensation	375		$ 0	375	0	0		0
Stock-based compensation (in shares)			0
Net income	98,225		$ 0	0	0	76,844		21,381
Net income (in shares)			0
Other comprehensive income	(35)		$ 0	0	(35)	0		0
Other comprehensive income (in shares)			0
Balance at Jun. 30, 2020	492,812		$ 1,015	1,260,017	(2)	(804,123)		35,905
Balance (in shares) at Jun. 30, 2020			101,392,000
Increase (Decrease) in Stockholders' Equity
Equity activity of noncontrolling interest from a consolidated variable interest entity	8		$ 0	0	0	0		8
Equity activity of noncontrolling interest from a consolidated variable interest entity (in shares)			0
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding	(12)		$ (1)	(11)	0	0		0
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding (in shares)			(1,000)
Stock-based compensation	441		$ 0	441	0	0		0
Stock-based compensation (in shares)			0
Net income	41,621		$ 0	0	0	28,218		13,403
Net income (in shares)			0
Other comprehensive income	2		$ 0	0	2	0		0
Other comprehensive income (in shares)			0
Balance at Sep. 30, 2020	534,872		$ 1,014	1,260,447	0	(775,905)		49,316
Balance (in shares) at Sep. 30, 2020			101,391,000
Balance at Dec. 31, 2020	$ 607,837	[1]	$ 1,014	1,260,900	0	(722,002)	$ 0	67,925
Balance (in shares) at Dec. 31, 2020	101,392,000		101,392,000				0
Increase (Decrease) in Stockholders' Equity
Distributions to noncontrolling interest	$ (21,285)		$ 0	0	0	0	$ 0	(21,285)
Distributions to noncontrolling interest (in shares)			0				0
Equity activity of noncontrolling interest from a consolidated variable interest entity	8		$ 0	0	0	0	$ 0	8
Equity activity of noncontrolling interest from a consolidated variable interest entity (in shares)			0				0
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding	(25)		$ 0	(25)	0	0	$ 0	0
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding (in shares)			16,000				0
Stock-based compensation	451		$ 0	451	0	0	$ 0	0
Stock-based compensation (in shares)			0				0
Net income	109,695		$ 0	0	0	94,123	$ 0	15,572
Net income (in shares)			0				0
Balance at Mar. 31, 2021	696,681		$ 1,014	1,261,326	0	(627,879)	$ 0	62,220
Balance (in shares) at Mar. 31, 2021			101,408,000				0
Balance at Dec. 31, 2020	$ 607,837	[1]	$ 1,014	1,260,900	0	(722,002)	$ 0	67,925
Balance (in shares) at Dec. 31, 2020	101,392,000		101,392,000				0
Increase (Decrease) in Stockholders' Equity
Net income	$ 323,187
Balance at Sep. 30, 2021	$ 491,805		$ 695	1,262,438	0	(466,493)	$ (393,829)	88,994
Balance (in shares) at Sep. 30, 2021	69,492,000		69,492,000				32,005,000
Balance at Mar. 31, 2021	$ 696,681		$ 1,014	1,261,326	0	(627,879)	$ 0	62,220
Balance (in shares) at Mar. 31, 2021			101,408,000				0
Increase (Decrease) in Stockholders' Equity
Distributions to noncontrolling interest	(20,161)		$ 0	0	0	0	$ 0	(20,161)
Distributions to noncontrolling interest (in shares)			0				0
Equity activity of noncontrolling interest from a consolidated variable interest entity	8		$ 0	0	0	0	$ 0	8
Equity activity of noncontrolling interest from a consolidated variable interest entity (in shares)			0				0
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding	50		$ 1	49	0	0	$ 0	0
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding (in shares)			92,000				0
Repurchase of common stock	(394,149)		$ (320)	0	0	0	$ (393,829)	0
Repurchase of common stock (in shares)			(32,005,000)				32,005,000
Stock-based compensation	470		$ 0	470	0	0	$ 0	0
Stock-based compensation (in shares)			0				0
Net income	110,846		$ 0	0	0	88,948	$ 0	21,898
Net income (in shares)			0				0
Balance at Jun. 30, 2021	393,745		$ 695	1,261,845	0	(538,931)	$ (393,829)	63,965
Balance (in shares) at Jun. 30, 2021			69,495,000				32,005,000
Increase (Decrease) in Stockholders' Equity
Distributions to noncontrolling interest	(4,912)		$ 0	0	0	0	$ 0	(4,912)
Distributions to noncontrolling interest (in shares)			0				0
Equity activity of noncontrolling interest from a consolidated variable interest entity	(267)		$ 0	0	0	0	$ 0	(267)
Equity activity of noncontrolling interest from a consolidated variable interest entity (in shares)			0				0
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding	51		$ 0	51	0	0	$ 0	0
Exercise of stock options, and issuance of common stock units and stock awards, net of repurchase of shares to satisfy tax withholding (in shares)			(3,000)				0
Stock-based compensation	542		$ 0	542	0	0	$ 0	0
Stock-based compensation (in shares)			0				0
Net income	102,646		$ 0	0	0	72,438	$ 0	30,208
Net income (in shares)			0				0
Balance at Sep. 30, 2021	$ 491,805		$ 695	$ 1,262,438	$ 0	$ (466,493)	$ (393,829)	$ 88,994
Balance (in shares) at Sep. 30, 2021	69,492,000		69,492,000				32,005,000

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