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 Earnings/(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)	(220,672)	(220,672)				(220,672)
Net unrealized gain on investments, net of tax	8,371	8,371					8,371
Repurchases of common stock under incentive plans		(716)		(716)
Issuance of common stock - stock offering		299,542	39		299,503
Issuance of common stock under benefit plans		298			298
Issuance of common stock under incentive plans		63	1		62
Amortization of restricted stock		3,375			3,375
Issuance of convertible debt		77,026			77,026
Stock-based compensation expense, net		21			21
Dividends declared		(767)			(767)
Balance, at Jun. 30, 2013		902,866	191	(892,810)	2,346,932	(575,913)	24,466
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)	377,592	377,592				377,592
Net unrealized gain on investments, net of tax	13,634	13,634					13,634
Repurchases of common stock under incentive plans		(154)		(154)
Issuance of common stock - stock offering		247,388	18		247,370
Issuance of common stock under benefit plans		487			487
Issuance of common stock under incentive plans		175			175
Amortization of restricted stock		5,002			5,002
Stock-based compensation expense, net		1,388			1,388
Dividends declared		(910)			(910)
Balance, at Jun. 30, 2014	$ 1,584,247	$ 1,584,247	$ 209	$ (892,961)	$ 2,600,616	$ (174,634)	$ 51,017