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			35,927,985			(21,643)
Shares issued pursuant to sale of equity			4,002,000
Issuance of stock awards, net of forfeitures			244,791
Treasury Stock Transactions, Excluding Value of Shares Reissued [Abstract]
Retirement of treasury shares						127,159
Issuance of treasury shares						(120,864)
Non-employee directors' deferred compensation plan						(4,872)
Stockholders' Equity Beginning, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2014		$ 1,137,359	$ 359	$ 689,209	$ 448,702	$ (911)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued pursuant to sale of equity			40	202,811
Purchase of treasury shares		202,851
Issuance of stock awards, net of forfeitures		3	3
Share-based Compensation expense	$ 20,068	21,568		21,568
Issuance of treasury shares		(6,055)				(6,055)
Retirement of treasury shares		0		(6,206)		6,206
Non-employee directors' deferred compensation plan		(249)				(249)
Net income (Loss) attributable to shareholders	(68,280)	(68,280)			(68,280)
Stockholders' Equity Ending, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2015		1,287,197	$ 402	907,382	380,422	$ (1,009)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Shares, Issued			40,174,776			(20,220)
Shares issued pursuant to sale of equity			15,007,500
Exercise of stock options			46,084
Issuance of stock awards, net of forfeitures			411,731
Stock Issued During Period, Value, Conversion of Convertible Securities			792,406
Stock Issued During Period, Value, Acquisitions			9,386,768
Treasury Stock Transactions, Excluding Value of Shares Reissued [Abstract]
Purchase of treasury shares						(116,085)
Issuance of treasury shares			(114,697)			114,697
Non-employee directors' deferred compensation plan						(7,155)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued pursuant to sale of equity		855,083	$ 150	854,933
Purchase of treasury shares		(6,935)				$ (6,935)
Issuance of stock awards, net of forfeitures		0	3	(3)
Share-based Compensation expense	19,502	19,502		19,502
Issuance of treasury shares		0		(6,661)		6,661
Non-employee directors' deferred compensation plan		(385)				(385)
Net income (Loss) attributable to shareholders	(245,928)	(245,928)			(245,928)
Cumulative Effect on Retained Earnings, Net of Tax					(286)
Stock Issued During Period, Value, Conversion of Convertible Securities		0	8	(8)
Stock Issued During Period, Value, Acquisitions		690,702	94	690,608
Adjustments to Additional Paid in Capital, Convertible Debt with Conversion Feature		23,518		23,518
Stockholders' Equity Ending, Including Portion Attributable to Noncontrolling Interest at Dec. 31, 2016		2,622,754	$ 657	2,489,557	134,208	$ (1,668)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders' Equity, Other		0		286
Shares, Issued			65,704,568			(28,763)
Issuance of stock awards, net of forfeitures			250,512
Purchase of treasury shares						(107,357)
Issuance of treasury shares						83,228
Non-employee directors' deferred compensation plan						(3,035)
Purchase of treasury shares		(6,672)				$ (6,672)
Issuance of stock awards, net of forfeitures		0	$ 2	(2)
Share-based Compensation expense	19,353	19,353		19,353
Issuance of treasury shares		0		(5,517)		5,517
Non-employee directors' deferred compensation plan		(185)				(185)
Net income (Loss) attributable to shareholders	$ (127,504)	(127,504)			(127,504)
Stockholders' Equity Ending, 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]
Stockholders' Equity, Other		$ (97)		$ (97)
Shares, Issued			65,955,080			(55,927)