CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]
Balance at Dec. 31, 2017	$ 66,321	$ 555	$ 25,337	$ (256,363)	$ 296,792
Purchase of treasury stock, at cost	(8,565)	0	0	(8,565)	0
Issuance of long-term incentive awards and dividend equivalents	0	0	(5,764)	6,619	(855)
Stock-based compensation expense	3,135	0	2,840	295	0
Other	(351)	0	(235)	(116)	0
Dividends paid	(8,402)	0	0	0	(8,402)
Unrealized gain on marketable securities, net of tax	1	0	0	0	1
Net income	49,991	0	0	0	49,991
Balance at Mar. 31, 2018	102,832	$ 555	22,648	(257,898)	337,527
Balance (shares) at Dec. 31, 2017		55,489
Balance (shares) at Mar. 31, 2018		55,489
Balance at Dec. 31, 2018	77,676	$ 555	36,752	(357,569)	397,938
Purchase of treasury stock, at cost	(29,037)	0	0	(29,037)	0
Issuance of long-term incentive awards and dividend equivalents	0	0	(7,695)	8,646	(951)
Stock-based compensation expense	6,040	0	4,340	1,700	0
Other	599	0	436	163	0
Dividends paid	(12,386)	0	0	0	(12,386)
Unrealized gain on marketable securities, net of tax	13	0	0	0	13
Net income	76,289	0	0	0	76,289
Balance at Mar. 31, 2019	$ 119,194	$ 555	$ 33,833	$ (376,097)	$ 460,903
Balance (shares) at Dec. 31, 2018		55,489
Balance (shares) at Mar. 31, 2019		55,489