Consolidated Statements of Stockholders' Equity - USD ($)	Total	Common Stock Shares [Member]	Treasury Stock-Common [Member]	Non-Redeemable Preferred Stock [Member]	Capital in Excess of Par Value [Member]	Retained Earnings [Member]
Balance at Dec. 31, 2013	$ 411,715,000	$ 2,685,000	$ (28,374,000)	$ 3,000,000	$ 167,550,000	$ 266,854,000
Balance, shares at Dec. 31, 2013		26,846,000	(4,320,000)
Net income (loss)	19,634,000					19,634,000
Dividends paid on convertible preferred stocks	(300,000)					(300,000)
Stock-based compensation	1,925,000				1,925,000
Exercise of stock options	1,074,000	$ 12,000			1,062,000
Exercise of stock options, shares		122,000
Excess income tax benefit associated with stock-based compensation	0
Balance at Dec. 31, 2014	434,048,000	$ 2,697,000	$ (28,374,000)	3,000,000	170,537,000	286,188,000
Balance, shares at Dec. 31, 2014		26,968,000	(4,320,000)
Net income (loss)	(34,765,000)					(34,765,000)
Dividends paid on convertible preferred stocks	(300,000)					(300,000)
Dividend accrued on redeemable preferred stock	(2,287,000)					(2,287,000)
Accretion of redeemable preferred stock	(686,000)					(686,000)
Stock-based compensation	2,346,000				2,346,000
Exercise of stock options	1,785,000	$ 16,000			1,769,000
Exercise of stock options, shares		160,000
Common stock issued for services	156,000				156,000
Common stock issued for services, shares		4,000
Restricted stock granted from treasury stock			$ 3,842,000		(3,842,000)
Restricted stock granted from treasury stock, shares			584,000
Common stock warrants issued	22,300,000				22,300,000
Common stock warrants issuance costs	(1,613,000)				(1,613,000)
Excess income tax benefit associated with stock-based compensation	596,000				596,000
Balance at Dec. 31, 2015	421,580,000	$ 2,713,000	$ (24,532,000)	3,000,000	192,249,000	248,150,000
Balance, shares at Dec. 31, 2015		27,132,000	(3,736,000)
Net income (loss)	112,168,000					112,168,000
Dividends paid on convertible preferred stocks	(300,000)
Dividend accrued on redeemable preferred stock	(27,761,000)					(27,761,000)
Accretion of redeemable preferred stock	(18,256,000)					(18,256,000)
Stock-based compensation	4,979,000				4,979,000
Exercise of stock options	$ 371,000	$ 4,000			367,000
Exercise of stock options, shares	45,215	45,000
Exercise of warrants, net		$ 411,000	$ (411,000)
Exercise of warrants, shares		4,104,000	(34,000)
Restricted stock granted from treasury stock	$ (484,000)		$ 4,855,000		(5,339,000)
Restricted stock granted from treasury stock, shares			765,000
Excess income tax benefit associated with stock-based compensation	0
Excess income tax detriment associated with stock-based compensation	(84,000)				(84,000)
Balance at Dec. 31, 2016	$ 492,513,000	$ 3,128,000	$ (20,088,000)	$ 3,000,000	$ 192,172,000	$ 314,301,000
Balance, shares at Dec. 31, 2016		31,281,000	(3,005,000)