Consolidated Statement of Equity (Statement) - USD ($) $ in Thousands	Total	Parent [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Shares, Issued			65,955,080			(55,927)
Issuance of stock awards, net of forfeitures			43,930
Treasury Stock Transactions, Excluding Value of Shares Reissued [Abstract]
Purchase of treasury shares						(41,357)
Issuance of treasury shares			0			70,603
Non-employee directors' deferred compensation plan						(2,574)
Stockholders' Equity Beginning, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2017		$ 2,507,649	$ 659	$ 2,503,294	$ 6,704	$ (3,008)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Purchase of treasury shares	$ (2,255)	(2,255)				(2,255)
Issuance of stock awards, net of forfeitures		0	1	(1)
Share-based Compensation expense	5,261	5,261		5,261
Issuance of treasury shares		0	0	(3,891)		3,891
Non-employee directors' deferred compensation plan		(142)		0		(142)
Net income (Loss) attributable to shareholders	(13,139)	(13,139)			(13,139)
Stockholders' Equity Ending, Including Portion Attributable to Noncontrolling Interest at Mar. 31, 2018		2,497,374	$ 660	$ 2,504,663	$ (6,435)	$ (1,514)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity, Other	$ 0	$ 0
Shares, Issued			65,999,010			(29,255)