Consolidated Statements of Changes in Stockholders' Equity - 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, 2015		354,541,626			3,124,311
Beginning balance at Dec. 31, 2015	$ 1,248,912	$ 355	$ 2,353,549	$ (1,058,954)	$ (46,038)
Cumulative effect of accounting change	15,657		(415)	16,072
Issued or purchased pursuant to stock compensation plans, shares		7,031,767
Issued or purchased pursuant to stock compensation plans, value	0	$ 7	(7)
Issued pursuant to directors' compensation plan, shares		31,930
Issued pursuant to directors' compensation plan, value	50		50
Issued as part of debt exchange, shares		40,729,332
Issued as part of debt exchange, value	160,491	$ 40	160,451
Issued pursuant to notes conversion, value	0
Stock-based compensation	$ 21,042		21,042
Tax withholding - stock compensation, shares	0				782,566
Tax withholding - stock compensation, value	$ (1,597)				$ (1,597)
Retirement of treasury stock, value					$ 0
Dividends adjustments	70			70
Net income (loss)	(976,177)			(976,177)
Ending balance, shares at Dec. 31, 2016		402,334,655			3,906,877
Ending balance at Dec. 31, 2016	468,448	$ 402	2,534,670	(2,018,989)	$ (47,635)
Issued or purchased pursuant to stock compensation plans, shares		5,201,854
Issued or purchased pursuant to stock compensation plans, value	0	$ 6	(6)
Issued pursuant to directors' compensation plan, shares		12,837
Issued pursuant to directors' compensation plan, value	0
Issued pursuant to notes conversion, value	0
Stock-based compensation	19,721		19,721
Tax withholding - stock compensation, shares					1,550,164
Tax withholding - stock compensation, value	(3,183)				$ (3,183)
Retirement of treasury stock, shares		(5,000,000)			(5,000,000)
Retirement of treasury stock, value	0	$ (5)	(46,557)		$ 46,562
Dividends adjustments	27			27
Net income (loss)	$ 163,152			163,152
Ending balance, shares at Dec. 31, 2017	402,549,346	402,549,346			457,041
Ending 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		4,556,424
Issued or purchased pursuant to stock compensation plans, value	0	$ 4	(4)
Issued pursuant to notes conversion, shares		55,249,955
Issued pursuant to notes conversion, value	162,004	$ 55	161,949
Stock-based compensation	15,438		15,438
Tax withholding - stock compensation, shares					1,484,708
Tax withholding - stock compensation, value	(6,528)				$ (6,528)
Retirement of treasury stock, value					$ 0
Net income (loss)	$ 322,698			322,698
Ending balance, shares at Dec. 31, 2018	462,355,725	462,355,725			1,941,749
Ending balance at Dec. 31, 2018	$ 1,141,777	$ 462	$ 2,685,211	$ (1,533,112)	$ (10,784)