Consolidated Statements of Changes in Equity (Unaudited) - USD ($)	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Total
Balance at Dec. 31, 2019	$ (697,223,000)	$ (25,000)	$ 2,157,000	$ 810,856,000	$ (14,024,000)	$ 101,741,000
Balance (in shares) at Dec. 31, 2019			21,573,000		930,000
Net income (loss)	(16,008,000)					(16,008,000)
Restricted stock awards, forfeitures and shares repurchased for tax withholdings, net				(32,000)	$ 104,000	72,000
Restricted stock awards, forfeitures and shares repurchased for tax withholdings, net (in shares)					(6,000)
Stock-based compensation expense				3,000		3,000
Balance at Mar. 31, 2020	(713,231,000)	(25,000)	$ 2,157,000	810,827,000	$ (13,920,000)	85,808,000
Balance (in shares) at Mar. 31, 2020			21,573,000		924,000
Balance at Dec. 31, 2019	(697,223,000)	(25,000)	$ 2,157,000	810,856,000	$ (14,024,000)	101,741,000
Balance (in shares) at Dec. 31, 2019			21,573,000		930,000
Net income (loss)						(25,919,000)
Balance at Jun. 30, 2020	(724,943,000)	(25,000)	$ 2,157,000	809,255,000	$ (12,130,000)	74,314,000
Balance (in shares) at Jun. 30, 2020			21,573,000		810,000
Balance at Dec. 31, 2019	(697,223,000)	(25,000)	$ 2,157,000	810,856,000	$ (14,024,000)	101,741,000
Balance (in shares) at Dec. 31, 2019			21,573,000		930,000
Balance at Dec. 31, 2020	(736,639,000)	(25,000)	$ 2,157,000	807,582,000	$ (10,200,000)	62,875,000
Balance (in shares) at Dec. 31, 2020			21,573,000		688,000
Balance at Mar. 31, 2020	(713,231,000)	(25,000)	$ 2,157,000	810,827,000	$ (13,920,000)	85,808,000
Balance (in shares) at Mar. 31, 2020			21,573,000		924,000
Net income (loss)	(9,911,000)					(9,911,000)
Restricted stock awards, forfeitures and shares repurchased for tax withholdings, net				(1,718,000)	$ 1,790,000	72,000
Restricted stock awards, forfeitures and shares repurchased for tax withholdings, net (in shares)					(114,000)
Stock-based compensation expense				146,000		146,000
Change in accounting at ownership interests	(1,801)					(1,801)
Balance at Jun. 30, 2020	(724,943,000)	(25,000)	$ 2,157,000	809,255,000	$ (12,130,000)	74,314,000
Balance (in shares) at Jun. 30, 2020			21,573,000		810,000
Balance at Dec. 31, 2020	(736,639,000)	(25,000)	$ 2,157,000	807,582,000	$ (10,200,000)	62,875,000
Balance (in shares) at Dec. 31, 2020			21,573,000		688,000
Net income (loss)	17,625,000					17,625,000
Restricted stock awards, forfeitures and shares repurchased for tax withholdings, net				(593,000)	$ 963,000	370,000
Restricted stock awards, forfeitures and shares repurchased for tax withholdings, net (in shares)					(58,000)
Stock-based compensation expense				122,000		122,000
Balance at Mar. 31, 2021	(719,014,000)	(25,000)	$ 2,157,000	807,111,000	$ (9,237,000)	80,992,000
Balance (in shares) at Mar. 31, 2021			21,573,000		630,000
Balance at Dec. 31, 2020	(736,639,000)	(25,000)	$ 2,157,000	807,582,000	$ (10,200,000)	62,875,000
Balance (in shares) at Dec. 31, 2020			21,573,000		688,000
Net income (loss)						17,305,000
Balance at Jun. 30, 2021	(719,334,000)	(25,000)	$ 2,157,000	806,447,000	$ (9,849,000)	79,396,000
Balance (in shares) at Jun. 30, 2021			21,573,000		786,000
Balance at Mar. 31, 2021	(719,014,000)	(25,000)	$ 2,157,000	807,111,000	$ (9,237,000)	80,992,000
Balance (in shares) at Mar. 31, 2021			21,573,000		630,000
Net income (loss)	(320,000)					(320,000)
Restricted stock awards, forfeitures and shares repurchased for tax withholdings, net				(839,000)	$ 976,000	137,000
Restricted stock awards, forfeitures and shares repurchased for tax withholdings, net (in shares)					(73,000)
Stock-based compensation expense				175,000		175,000
Repurchases of common stock					$ (1,588,000)	(1,588,000)
Repurchases of common stock (in shares)					229
Balance at Jun. 30, 2021	$ (719,334,000)	$ (25,000)	$ 2,157,000	$ 806,447,000	$ (9,849,000)	$ 79,396,000
Balance (in shares) at Jun. 30, 2021			21,573,000		786,000