Condensed Consolidated Statement Of Stockholders' Equity - 6 months ended Jun. 30, 2015 - USD ($) $ in Thousands	Total	Common Stock	Paid-in Capital	Retained Earnings	Treasury Stock
December 31, 2014 at Dec. 31, 2014	$ 394,898	$ 265	$ 147,186	$ 276,914	$ (29,467)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	40,942			40,942
Issuance of 292,430 shares of common stock pursuant to stock-based awards, net of shares tendered for payment of taxes	(7,008)	3	(7,011)
Income tax benefit relating to issuance of common stock pursuant to stock-based awards	6,320		6,320
Stock-based compensation expense	7,069		7,069
Issuance of 36,579 deferred stock units relating to prior year compensation	2,046		2,046
Special cash dividend ($2.00 per share)	(48,227)			(48,227)
Dividend equivalents on stock-based awards			1,826	(1,826)
June 30, 2015 at Jun. 30, 2015	$ 396,040	$ 268	$ 157,436	$ 267,803	$ (29,467)