Condensed Consolidated Statement Of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Paid-in Capital	Retained Earnings	Treasury Stock
Balance - at Dec. 31, 2012	$ 284,245	$ 254	$ 100,412	$ 213,046	$ (29,467)
Net income	50,119			50,119
Issuance of shares of common stock pursuant to stock options, deferred stock units and restricted stock	13,447	7	13,440
Income tax benefit relating to issuance of common stock pursuant to stock-based awards	1,534		1,534
Stock-based compensation expense	10,839		10,839
Issuance of deferred stock units relating to prior year compensation	135		135
Special cash dividend ($2.00 per share)	(46,706)			(46,706)
Balance - at Dec. 31, 2013	313,613	261	126,360	216,459	(29,467)
Net income	62,266			62,266
Issuance of shares of common stock pursuant to stock options, deferred stock units and restricted stock	2,302	4	2,298
Income tax benefit relating to issuance of common stock pursuant to stock-based awards	3,914		3,914
Stock-based compensation expense	10,817		10,817
Issuance of deferred stock units relating to prior year compensation	1,986		1,986
Special cash dividend ($2.00 per share)	0			(1,811)
Dividend equivalents on stock-based awards			1,811
Balance - at Dec. 31, 2014	394,898	265	147,186	276,914	(29,467)
Net income	74,345			74,345
Issuance of shares of common stock pursuant to stock options, deferred stock units and restricted stock	(7,558)	5	(7,563)
Income tax benefit relating to issuance of common stock pursuant to stock-based awards	9,028		9,028
Stock-based compensation expense	14,043		14,043
Issuance of 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)
Balance - at Dec. 31, 2015	$ 438,575	$ 270	$ 166,566	$ 301,206	$ (29,467)