Condensed Consolidated Statements of Changes in Common Stockholders' Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	Total	Parent	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Deficit	Accumulated Other Comprehensive Income (Loss)
Balance, at Dec. 31, 2012		$ 736,325	$ 151	$ (892,094)	$ 1,967,414	$ (355,241)	$ 16,095
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(233,354)	(233,354)				(233,354)
Net foreign currency translation adjustment, net of tax	0
Net unrealized gain on investments, net of tax	13,045	13,045					13,045
Repurchases of common stock under incentive plans		(713)		(713)
Issuance of common stock - stock offering		299,410	39		299,371
Issuance of common stock under benefit plans		643			643
Issuance of common stock under incentive plans		63	1		62
Amortization of restricted stock		3,883			3,883
Issuance of convertible debt		77,026			77,026
Stock-based compensation expense, net		(608)			(608)
Dividends declared		(1,200)			(1,200)
Balance, at Sep. 30, 2013		894,520	191	(892,807)	2,346,591	(588,595)	29,140
Balance, at Dec. 31, 2013	939,645	939,645	191	(892,807)	2,347,104	(552,226)	37,383
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	531,182	531,182				531,182
Net foreign currency translation adjustment, net of tax	(186)	(186)					(186)
Net unrealized gain on investments, net of tax	11,817	11,817					11,817
Repurchases of common stock under incentive plans		(154)		(154)
Issuance of common stock - stock offering		247,188	18		247,170
Issuance of common stock under benefit plans		922			922
Issuance of common stock under incentive plans		175			175
Amortization of restricted stock		6,283			6,283
Stock-based compensation expense, net		(1,083)			(1,083)
Dividends declared		(1,388)			(1,388)
Balance, at Sep. 30, 2014	$ 1,734,401	$ 1,734,401	$ 209	$ (892,961)	$ 2,599,183	$ (21,044)	$ 49,014