Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Treasury Stock-Common [Member]	Capital in Excess of Par Value [Member]	Retained Earnings [Member]	Non-Redeemable Preferred Stock [Member]
Balance at Dec. 31, 2017	$ 438,196	$ 3,128	$ (18,102)	$ 193,956	$ 256,214	$ 3,000
Balance, shares at Dec. 31, 2017		31,281	(2,662)
Net loss	(72,226)				(72,226)
Dividend accrued on redeemable preferred stock	(26,840)				(26,840)
Accretion of redeemable preferred stock	(3,375)				(3,375)
Stock-based compensation	8,358			8,358
Restricted stock granted from treasury stock	(1,936)		$ 1,916	(3,852)
Restricted stock granted from treasury stock, shares			224
Other	20			20
Other, Shares		2
Balance at Dec. 31, 2018	342,197	$ 3,128	$ (16,186)	198,482	153,773	3,000
Balance, shares at Dec. 31, 2018		31,283	(2,438)
Net loss	(63,417)				(63,417)
Dividend accrued on redeemable preferred stock	(30,729)				(30,729)
Accretion of redeemable preferred stock	(1,995)				(1,995)
Stock-based compensation	2,220			2,220
Restricted stock granted from treasury stock	(949)		$ 2,920	(3,869)
Restricted stock granted from treasury stock, shares			428
Balance at Dec. 31, 2019	247,327	$ 3,128	$ (13,266)	196,833	57,632	3,000
Balance, shares at Dec. 31, 2019		31,283	(2,010)
Net loss	(61,911)				(61,911)
Dividend accrued on redeemable preferred stock	(35,182)				(35,182)
Accretion of redeemable preferred stock	(2,026)				(2,026)
Stock-based compensation	1,761			1,761
Restricted stock granted from treasury stock			$ 379	(379)
Restricted stock granted from treasury stock, shares			58
Acquisition of shares withheld for employee taxes	326		$ 326
Acquisition of shares withheld for employee taxes, shares			(123)
Balance at Dec. 31, 2020	$ 149,643	$ 3,128	$ (13,213)	$ 198,215	$ (41,487)	$ 3,000
Balance, shares at Dec. 31, 2020		31,283	(2,075)