Consolidated Statement of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance, shares at Dec. 31, 2014		109,353,000
Beginning balance at Dec. 31, 2014	$ 1,389,395	$ 1,094	$ 813,178	$ 1,927,445	$ (1,347,677)	$ (4,645)
Net earnings (loss)	(953,520)			(953,520)
Total other comprehensive income (loss)	(6,399)					(6,399)
Exercise of stock options, shares		66,000
Exercise of stock options	1,485		1,485
Vesting of restricted share units, shares		23,000
Vesting of restricted share units	0	$ 0
Tax effect of stock awards vested and options expired	(5,865)		(5,865)
Adjustments to Additional Paid in Capital, Share-based Compensation, Stock Options, Requisite Service Period Recognition	9,541		9,541
Dividends declared	(51,047)			(51,047)
Ending balance, shares at Dec. 31, 2015		109,442,000
Ending balance at Dec. 31, 2015	383,590	$ 1,094	818,339	922,878	(1,347,677)	(11,044)
Net earnings (loss)	(105,195)			(105,195)
Total other comprehensive income (loss)	(5,188)					(5,188)
Vesting of restricted share units, shares		77,000
Vesting of restricted share units	0	$ 1	(1)
Tax effect of stock awards vested and options expired	(440)		(440)
Adjustments to Additional Paid in Capital, Share-based Compensation, Stock Options, Requisite Service Period Recognition	9,209		9,209
Dividends declared	(17,043)			(17,043)
Ending balance, shares at Dec. 31, 2016		109,519,000
Ending balance at Dec. 31, 2016	264,933	$ 1,095	827,107	800,640	(1,347,677)	(16,232)
Net earnings (loss)	6,653			6,653
Total other comprehensive income (loss)	$ 5,241					5,241
Exercise of stock options, shares	38,830	27,000
Exercise of stock options	$ 270		270
Vesting of restricted share units, shares		136,000
Vesting of restricted share units	0	$ 2	(2)
Adjustments to Additional Paid in Capital, Share-based Compensation, Stock Options, Requisite Service Period Recognition	3,896		3,896
Dividends declared	(8,550)			(8,550)
Ending balance, shares at Dec. 31, 2017		109,682,000
Ending balance at Dec. 31, 2017	$ 272,443	$ 1,097	$ 831,271	$ 798,743	$ (1,347,677)	$ (10,991)