Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands		Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings
Beginning Balance at Dec. 31, 2013		$ 1,065,350	$ 439	$ 762,242	$ (12,575)	$ 315,244
Stock issued for benefit plans		1,909	0	(1,876)	3,785	0
Purchase of treasury shares		(1,065)	0	0	(1,065)	0
Employee stock purchase plan		824	1	823	0	0
Issuance of restricted stock		0	4	(4)	0	0
Amortization of share-based compensation		10,787	0	10,787	0	0
Net Income		(283,427)	0	0	0	(283,427)
Ending Balance at Dec. 31, 2014		794,378	444	771,972	(9,855)	31,817
Stock issued for benefit plans		919	0	(1,714)	7,518	(4,885)
Purchase of treasury shares		(150)	0	0	(150)	0
Employee stock purchase plan		302	1	301	0	0
Issuance of restricted stock		0	2	(2)	0	0
Amortization of share-based compensation		2,765	0	2,765	0	0
Net Income		(769,944)	0	0	0	(769,944)
Ending Balance at Jun. 30, 2015	[1]	$ 28,270	$ 447	$ 773,322	$ (2,487)	$ (743,012)

[1] Unaudited