Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Preferred stock	Common stock	Other paid-in capital	Retained earnings	Total accumulated other comprehensive loss	Treasury stock	Noncontrolling interest
Balance (in shares) at Dec. 31, 2015		150,000
Balance (in shares) at Dec. 31, 2014			194,754,812
Treasury stock (in shares) at Dec. 31, 2014							(538,921)
Balance at Dec. 31, 2014	$ 3,249,784	$ 15,000	$ 194,755	$ 1,207,188	$ 1,762,827	$ (42,103)	$ (3,626)	$ 115,743
Net income (loss) attributable to parent					(622,435)
Net loss attributable to noncontrolling interest								(35,256)
Net income (loss)	(657,691)
Other comprehensive income (loss)	4,955					4,955
Dividends declared on preferred stocks	(685)				(685)
Dividends declared on common stock	(143,352)				(143,352)
Stock-based compensation	3,689			3,689
Net tax deficit on stock-based compensation	(1,606)			(1,606)
Issuance of common stock (in shares)			1,049,853
Issuance of common stock	21,898		$ 1,050	20,848
Contribution from non-controlling interest	52,000							52,000
Distribution to non-controlling interest	(8,444)							(8,444)
Tax withholding on stock-based compensation	0
Redemption of preferred stock - premium	0
Redemption of preferred stock	0
Balance (in shares) at Dec. 31, 2014		150,000
Balance (in shares) at Dec. 31, 2015			195,804,665
Treasury stock (in shares) at Dec. 31, 2015							(538,921)
Balance at Dec. 31, 2015	2,520,548	$ 15,000	$ 195,805	1,230,119	996,355	(37,148)	$ (3,626)	124,043
Balance (in shares) at Dec. 31, 2016		150,000
Net income (loss) attributable to parent					64,433
Net loss attributable to noncontrolling interest								(131,691)
Net income (loss)	(67,258)
Other comprehensive income (loss)	1,415					1,415
Dividends declared on preferred stocks	(685)				(685)
Dividends declared on common stock	(147,821)				(147,821)
Stock-based compensation	4,383			4,383
Net tax deficit on stock-based compensation	(1,663)			(1,663)
Contribution from non-controlling interest	7,648							7,648
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings (in shares)			38,632
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings			$ 38
Issuance of common stock upon vesting of stock-based compensation, gross				(361)
Tax withholding on stock-based compensation	(323)
Redemption of preferred stock - premium	0
Redemption of preferred stock	$ 0
Balance (in shares) at Dec. 31, 2015		150,000
Balance (in shares) at Dec. 31, 2016	195,843,297		195,843,297
Treasury stock (in shares) at Dec. 31, 2016	(538,921)						(538,921)
Balance at Dec. 31, 2016	$ 2,316,244	$ 15,000	$ 195,843	1,232,478	912,282	(35,733)	$ (3,626)	0
Balance (in shares) at Dec. 31, 2017		0
Net income (loss) attributable to parent					281,203
Net income (loss)	281,203
Other comprehensive income (loss)	(1,601)					(1,601)
Dividends declared on preferred stocks	(171)				(171)
Dividends declared on common stock	(151,966)				(151,966)
Stock-based compensation	3,375			3,375
Issuance of common stock upon vesting of stock-based compensation, gross				(2,441)
Tax withholding on stock-based compensation	(757)
Repurchase of common stock (in shares)							(64,384)
Repurchase of common stock	(1,684)						$ (1,684)
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings - treasury stock (in shares)							64,384
Issuance of common stock upon vesting of stock-based compensation, net of shares used for tax withholdings - treasury stock							$ 1,684
Redemption of preferred stock (in shares)		(150,000)
Redemption of preferred stock - amount		$ (15,000)
Redemption of preferred stock - premium	(600)				(600)
Redemption of preferred stock	$ (15,600)
Balance (in shares) at Dec. 31, 2016		150,000
Balance (in shares) at Dec. 31, 2017	195,843,297		195,843,297
Treasury stock (in shares) at Dec. 31, 2017	(538,921)						(538,921)
Balance at Dec. 31, 2017	$ 2,429,043	$ 0	$ 195,843	$ 1,233,412	$ 1,040,748	$ (37,334)	$ (3,626)	$ 0