CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (Unaudited) - 9 months ended Sep. 30, 2018 - 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	(16,236)	0	0	(16,236)	0
Issuance of long-term incentive awards and dividend equivalents	0	0	(5,764)	6,619	(855)
Stock-based compensation expense	14,656	0	11,293	3,363	0
Other	1,611	0	1,181	430	0
Dividends paid	(25,170)	0	0	0	(25,170)
Unrealized loss on marketable securities, net of tax	(20)	0	0	0	(20)
Net income	110,758	0	0	0	110,758
Balance at Sep. 30, 2018	$ 151,920	$ 555	$ 32,047	$ (262,187)	$ 381,505
Balance (shares) at Dec. 31, 2017		55,489
Balance (shares) at Sep. 30, 2018		55,489