CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive (Loss) Income	Total
Balance at Dec. 31, 2018	$ 21,454		$ 947,711	$ (18,746)	$ 950,419
Balance (in shares) at Dec. 31, 2018	214,544
Increase (Decrease) in Stockholders' Equity
Stock issued for stock incentive plans, net	$ 84	$ 2,368			2,452
Stock issued for stock incentive plans, net (in shares)	843
Stock purchased and retired	$ (24)	(2,368)	(306)		(2,698)
Stock purchased and retired (in shares)	(245)
Net (loss) income			(739)		(739)
Dividends			(21,486)		(21,486)
Pension adjustment, net of taxes				173	173
Foreign currency translation				98	98
Balance at Mar. 31, 2019	$ 21,514		927,556	(21,207)	927,863
Balance (in shares) at Mar. 31, 2019	215,142
Balance at Dec. 31, 2018	$ 21,454		947,711	(18,746)	950,419
Balance (in shares) at Dec. 31, 2018	214,544
Increase (Decrease) in Stockholders' Equity
Net (loss) income					5,432
Foreign currency translation					431
Balance at Jun. 30, 2019	$ 21,458		920,917	(20,700)	921,675
Balance (in shares) at Jun. 30, 2019	214,579
Increase (Decrease) in Stockholders' Equity
Adoption of accounting standards (Note 2)			2,376	(2,732)	(356)
Balance at Mar. 31, 2019	$ 21,514		927,556	(21,207)	927,863
Balance (in shares) at Mar. 31, 2019	215,142
Increase (Decrease) in Stockholders' Equity
Stock issued for stock incentive plans, net	$ (2)	2,438			2,436
Stock issued for stock incentive plans, net (in shares)	(23)
Stock purchased and retired	$ (54)	(2,438)	(2,159)		(4,651)
Stock purchased and retired (in shares)	(540)
Net (loss) income			6,171		6,171
Dividends			(10,738)		(10,738)
Pension adjustment, net of taxes				174	174
Foreign currency translation				333	333
Balance at Jun. 30, 2019	$ 21,458		920,917	(20,700)	921,675
Balance (in shares) at Jun. 30, 2019	214,579
Increase (Decrease) in Stockholders' Equity
Adoption of accounting standards (Note 2)			87		87
Balance at Dec. 31, 2019	$ 21,443		832,113	(23,223)	830,333
Balance (in shares) at Dec. 31, 2019	214,423
Increase (Decrease) in Stockholders' Equity
Stock issued for stock incentive plans, net	$ 100	1,997			2,097
Stock issued for stock incentive plans, net (in shares)	1,014
Stock purchased and retired	$ (17)	(1,997)	1,222		(792)
Stock purchased and retired (in shares)	(177)
Net (loss) income			(160,423)		(160,423)
Pension adjustment, net of taxes				732	732
Foreign currency translation				(712)	(712)
Balance at Mar. 31, 2020	$ 21,526		672,912	(23,203)	671,235
Balance (in shares) at Mar. 31, 2020	215,260
Balance at Dec. 31, 2019	$ 21,443		832,113	(23,223)	830,333
Balance (in shares) at Dec. 31, 2019	214,423
Increase (Decrease) in Stockholders' Equity
Net (loss) income					(185,516)
Foreign currency translation					(398)
Balance at Jun. 30, 2020	$ 21,512		649,844	(22,703)	648,653
Balance (in shares) at Jun. 30, 2020	215,123
Balance at Mar. 31, 2020	$ 21,526		672,912	(23,203)	671,235
Balance (in shares) at Mar. 31, 2020	215,260
Increase (Decrease) in Stockholders' Equity
Stock issued for stock incentive plans, net	$ (4)	2,021			2,017
Stock issued for stock incentive plans, net (in shares)	(135)
Stock purchased and retired	$ (10)	$ (2,021)	2,025		(6)
Stock purchased and retired (in shares)	(2)
Net (loss) income			(25,093)		(25,093)
Pension adjustment, net of taxes				186	186
Foreign currency translation				314	314
Balance at Jun. 30, 2020	$ 21,512		$ 649,844	$ (22,703)	$ 648,653
Balance (in shares) at Jun. 30, 2020	215,123