Consolidated Statement of Stockholders' Equity (Unaudited) - 9 months ended Sep. 30, 2017 - 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, 2016	41,098
Balance at Dec. 31, 2016	$ 459	$ 258,880	$ 644,308	$ (105,864)	$ 797,783
Net income			34,582		34,582
Share-based compensation (in shares)	76
Share-based compensation	$ 1	2,532			2,533
Exercise of stock options (in shares)	31
Exercise of stock options		482			482
Quarterly cash dividends of $0.15 per share of common stock			(18,551)		(18,551)
Repurchases of common stock (in shares)	(220)
Repurchases of common stock				(4,348)	(4,348)
Balance (in shares) at Sep. 30, 2017	40,985
Balance at Sep. 30, 2017	$ 460	$ 261,894	$ 660,339	$ (110,212)	$ 812,481