Consolidated Statement of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Total
Balance (in shares) at Dec. 31, 2017	40,992
Balance at Dec. 31, 2017	$ 461	$ 262,885	$ 769,426	$ (111,982)	$ 920,790
Net income (loss)			(2,320)		(2,320)
Share-based compensation (in shares)	60
Share-based compensation	$ 1	846			847
Quarterly cash dividends of common stock			(6,224)		(6,224)
Repurchases of common stock (in shares)	(87)
Repurchases of common stock				(1,689)	(1,689)
Balance (in shares) at Mar. 31, 2018	40,965
Balance at Mar. 31, 2018	$ 462	263,731	760,882	(113,671)	911,404
Balance (in shares) at Dec. 31, 2018	40,854
Balance at Dec. 31, 2018	$ 463	266,366	785,251	(117,325)	934,755
Net income (loss)			8,554		8,554
Share-based compensation (in shares)	63
Share-based compensation	$ 1	788			789
Quarterly cash dividends of common stock			(6,198)		(6,198)
Repurchases of common stock (in shares)	(88)
Repurchases of common stock				(1,482)	(1,482)
Balance (in shares) at Mar. 31, 2019	40,829
Balance at Mar. 31, 2019	$ 464	$ 267,154	$ 787,607	$ (118,807)	$ 936,418