CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Paid-in Capital	Retained Earnings (Accumulated Deficit)	Deferred Compensation Obligation	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Balance as of beginning of period (in shares) at Dec. 31, 2012			55,117,000
Balance as of beginning of period at Dec. 31, 2012	$ 895,116	$ 1,150	$ 364	$ 849,046	$ 45,790	$ 3,111	$ (982)	$ (3,363)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(143,070)				(143,070)
Dividends declared on preferred stock	(6,900)				(6,900)
Issuance of stock (in shares)			10,000,000
Issuance of common stock	42,141		$ 100	42,041
Induced conversion of preferred stock	0
Share-based compensation (in shares)			78,000
Share-based compensation	5,781		$ 1	5,780
Deferred compensation (in shares)			31,000
Deferred compensation	(677)			(679)		(319)		321
Exercise of stock options (in shares)			3,000
Exercise of stock options	16			16
Restricted stock unit vesting (in shares)			78,000
Restricted stock unit vesting	(251)		$ 1	(252)
Change in pension and postretirement benefit obligations	1,249						1,249
Other	4,601			4,601
Balance as of end of period (in shares) at Dec. 31, 2013			65,307,000
Balance as of end of period at Dec. 31, 2013	788,804	1,150	$ 466	891,351	(104,180)	2,792	267	(3,042)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(409,592)				(409,592)
Issuance of common stock (shares)			0
Issuance of preferred stock	313,330			310,080
Dividends declared on preferred stock	(17,148)				(17,148)
Issuance of preferred stock		3,250
Conversion of preferred stock (in shares)			5,926,000
Conversion of preferred stock	0	(356)	$ 59	297
Induced conversion of preferred stock	(4,256)				(4,256)
Share-based compensation (in shares)			15,000
Share-based compensation	3,627		$ 1	3,626
Deferred compensation (in shares)			0
Deferred compensation	116			0		419		(303)
Exercise of stock options (in shares)			257,000
Exercise of stock options	1,428		$ 3	1,425
Restricted stock unit vesting (in shares)			64,000
Restricted stock unit vesting	(474)		$ 0	(474)
Change in pension and postretirement benefit obligations	(18)						(18)
Balance as of end of period (in shares) at Dec. 31, 2014			71,569,000
Balance as of end of period at Dec. 31, 2014	675,817	4,044	$ 529	1,206,305	(535,176)	3,211	249	(3,345)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(1,582,961)				(1,582,961)
Dividends declared on preferred stock	(12,134)				(12,134)
Conversion of preferred stock (in shares)			9,414,000
Conversion of preferred stock	0	(898)	$ 94	804
Induced conversion of preferred stock	0
Share-based compensation (in shares)			195,000
Share-based compensation	4,540		$ 4	4,536
Deferred compensation (in shares)			2,000
Deferred compensation	$ 0			0		229		(229)
Exercise of stock options (in shares)	0
Restricted stock unit vesting (in shares)			73,000
Restricted stock unit vesting	$ (556)		$ 1	(557)
Change in pension and postretirement benefit obligations	173						173
Balance as of end of period (in shares) at Dec. 31, 2015			81,253,000
Balance as of end of period at Dec. 31, 2015	$ (915,121)	$ 3,146	$ 628	$ 1,211,088	$ (2,130,271)	$ 3,440	$ 422	$ (3,574)