Consolidated Statements Of Stockholders' Equity (Unaudited) - 6 months ended Jun. 30, 2015 - USD ($) shares in Thousands, $ in Thousands	Total		Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income, net of taxes	Retained Earnings	Treasury Stock
Balance (in shares) at Dec. 31, 2014			72,878
Balance at Dec. 31, 2014	$ 275,830		$ 729	$ 186,022	$ 25	$ 100,237	$ (11,183)
Comprehensive income:
Net income for the period	31,804					31,804
Unrealized loss on available for sale marketable securities, net of taxes	(17)	[1]			(17)
Total comprehensive income	31,787
Exercise of stock options, net of shares tendered for payment (in shares)			237
Exercise of stock options, net of shares tendered for payment	4,085		$ 2	4,083
Tax benefit from equity compensation plans	817			817
Share-based compensation expense — stock options and restricted stock	1,528			1,528
Treasury shares issued for Deferred Compensation Plan funding and redemptions	492			436			56
Shares issued pursuant to Employee Stock Purchase Plan	1,701			1,363			338
Cash dividends	(25,415)					(25,415)
Shares issued pursuant to Dividend Reinvestment Plan	54			169			(115)
Shares issued pursuant to prior year acquisition (in shares)			176
Shares issued pursuant to prior year acquisition	0		$ 2	(2)
Balance (in shares) at Jun. 30, 2015			73,291
Balance at Jun. 30, 2015	$ 290,879		$ 733	$ 194,416	$ 8	$ 106,626	$ (10,904)

[1] All amounts are net of tax.