UNAUDITED CONDENSED CONSOLIDATED STATEMENT OF CHANGES IN STOCKHOLDERS’ EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Retained Earnings	Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of new accounting standard (Note C), net of tax of $63	$ (179)				$ (179)
Shares at beginning of period (in shares) at Dec. 31, 2017		71,494				45,167
Balance at beginning of period at Dec. 31, 2017	134,277	$ 715	$ 437,394	$ 100	195,143	$ (499,075)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	25,447				25,447
Issuance for stock-based compensation and dividends, net of forfeitures (in shares)		97
Issuance for stock-based compensation and dividends, net of forfeitures	0	$ 1	324		(325)
Exercise of stock options (in shares)		5				1
Exercise of stock options	0	$ 0	46			$ (46)
Stock-based compensation expense	4,552		4,552
Employee stock purchase plan	261		144			$ 117
Employee stock purchase plan (in shares)						(11)
Dividends ($0.24 per share)	(5,943)				(5,943)
Change in fair value of interest rate swap, net of tax of $237	697			697
Repurchases of common stock (in shares)						322
Repurchases of common stock	(8,806)					$ (8,806)
Shares at end of period (in shares) at Jun. 30, 2018		71,596				45,479
Balance at end of period at Jun. 30, 2018	$ 150,306	$ 716	$ 442,460	$ 797	$ 214,143	$ (507,810)