Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock [Member]	Paid-in Capital [Member]	Treasury Stock, at Cost [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance at Dec. 31, 2012	$ 2,854,567	$ 2,141	$ 3,026,823	$ (53,848)	$ (104,042)	$ (16,507)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)	(587,633)				(641,832)	54,199
Dividends on common shares	(25,475)				(25,475)
Issuance of shares of common stock under the stock incentive plan — restricted stock and restricted stock units, net of forfeitures	0	0	0
Employee stock-based compensation expense	11,790		11,790
Ending Balance at Dec. 31, 2013	2,253,249	2,141	3,038,613	(53,848)	(771,349)	37,692
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)	(592,804)				(558,353)	(34,451)
Dividends on common shares	(2,123)				(2,123)
Treasury shares purchased	(15)	0	0	(15)
Employee stock-based compensation expense	9,847		9,847
Ending Balance at Dec. 31, 2014	1,668,154	2,141	3,048,460	(53,863)	(1,331,825)	3,241
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Total comprehensive income (loss)	(2,918,198)				(2,913,142)
Issuance of shares of common stock under the stock incentive plan — restricted stock and restricted stock units, net of forfeitures	(5)	4	(9)
Employee stock-based compensation expense	5,760
Ending Balance at Dec. 31, 2015	$ (1,244,289)	$ 2,145	$ 3,054,211	$ (53,863)	$ (4,244,967)	$ (1,815)