Condensed Consolidated Statement of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock ($.001 Par Value)	Paid-In Capital in Excess of Par	Retained Earnings (Accumulated Deficit)	Treasury Stock (at cost)
Beginning balance, shares at Dec. 31, 2017		402,549,346			457,041
Beginning balance at Dec. 31, 2017	$ 648,165	$ 403	$ 2,507,828	$ (1,855,810)	$ (4,256)
Issued or purchased pursuant to stock compensation plans, shares		378,595
Stock-based compensation, value	3,303		3,303
Tax withholding - stock compensation, shares					330,826
Tax withholding - stock compensation, value	(828)				$ (828)
Net income (loss)	39,578			39,578
Ending balance, shares at Mar. 31, 2018		402,927,941			787,867
Ending balance at Mar. 31, 2018	690,218	$ 403	2,511,131	(1,816,232)	$ (5,084)
Beginning balance, shares at Dec. 31, 2017		402,549,346			457,041
Beginning balance at Dec. 31, 2017	648,165	$ 403	2,507,828	(1,855,810)	$ (4,256)
Net income (loss)	148,219
Ending balance, shares at Sep. 30, 2018		462,462,855			1,893,882
Ending balance at Sep. 30, 2018	963,184	$ 462	2,680,899	(1,707,591)	$ (10,586)
Beginning balance, shares at Mar. 31, 2018		402,927,941			787,867
Beginning balance at Mar. 31, 2018	690,218	$ 403	2,511,131	(1,816,232)	$ (5,084)
Issued or purchased pursuant to stock compensation plans, shares		36,437
Issued pursuant to notes conversion, shares		55,249,999
Issued pursuant to notes conversion, value	162,050	$ 55	161,995
Stock-based compensation, value	3,226		3,226
Tax withholding - stock compensation, shares					18,451
Tax withholding - stock compensation, value	(71)				$ (71)
Net income (loss)	30,222			30,222
Ending balance, shares at Jun. 30, 2018		458,214,377			806,318
Ending balance at Jun. 30, 2018	885,645	$ 458	2,676,352	(1,786,010)	$ (5,155)
Issued or purchased pursuant to stock compensation plans, shares		4,248,522
Issued or purchased pursuant to stock compensation plans, value		$ 4	(4)
Issued pursuant to notes conversion, shares		(44)
Issued pursuant to notes conversion, value	(46)		(46)
Stock-based compensation, value	4,597		4,597
Tax withholding - stock compensation, shares					1,087,564
Tax withholding - stock compensation, value	(5,431)				$ (5,431)
Net income (loss)	78,419			78,419
Ending balance, shares at Sep. 30, 2018		462,462,855			1,893,882
Ending balance at Sep. 30, 2018	$ 963,184	$ 462	2,680,899	(1,707,591)	$ (10,586)
Beginning balance, shares at Dec. 31, 2018	462,355,725	462,355,725			1,941,749
Beginning balance at Dec. 31, 2018	$ 1,141,777	$ 462	2,685,211	(1,533,112)	$ (10,784)
Issued or purchased pursuant to stock compensation plans, shares		1,331,050
Issued or purchased pursuant to stock compensation plans, value	2	$ 2
Issued pursuant to directors' compensation plan, shares		41,487
Stock-based compensation, value	4,306		4,306
Tax withholding - stock compensation, shares					531,494
Tax withholding - stock compensation, value	(1,091)				$ (1,091)
Net income (loss)	(25,674)			(25,674)
Ending balance, shares at Mar. 31, 2019		463,728,262			2,473,243
Ending balance at Mar. 31, 2019	$ 1,119,320	$ 464	2,689,517	(1,558,786)	$ (11,875)
Beginning balance, shares at Dec. 31, 2018	462,355,725	462,355,725			1,941,749
Beginning balance at Dec. 31, 2018	$ 1,141,777	$ 462	2,685,211	(1,533,112)	$ (10,784)
Net income (loss)	$ 193,880
Ending balance, shares at Sep. 30, 2019	473,213,227	473,213,227			3,620,785
Ending balance at Sep. 30, 2019	$ 1,346,120	$ 473	2,698,158	(1,339,232)	$ (13,279)
Beginning balance, shares at Mar. 31, 2019		463,728,262			2,473,243
Beginning balance at Mar. 31, 2019	1,119,320	$ 464	2,689,517	(1,558,786)	$ (11,875)
Issued or purchased pursuant to stock compensation plans, shares		400,850
Issued pursuant to directors' compensation plan, shares		37,367
Stock-based compensation, value	4,667		4,667
Tax withholding - stock compensation, shares					1,661
Tax withholding - stock compensation, value	(3)				$ (3)
Net income (loss)	146,692			146,692
Ending balance, shares at Jun. 30, 2019		464,166,479			2,474,904
Ending balance at Jun. 30, 2019	1,270,676	$ 464	2,694,184	(1,412,094)	$ (11,878)
Issued or purchased pursuant to stock compensation plans, shares		9,046,748
Issued or purchased pursuant to stock compensation plans, value		$ 9	(9)
Stock-based compensation, value	3,983		3,983
Tax withholding - stock compensation, shares					1,145,881
Tax withholding - stock compensation, value	(1,401)				$ (1,401)
Net income (loss)	$ 72,862			72,862
Ending balance, shares at Sep. 30, 2019	473,213,227	473,213,227			3,620,785
Ending balance at Sep. 30, 2019	$ 1,346,120	$ 473	$ 2,698,158	$ (1,339,232)	$ (13,279)