Condensed Consolidated Statement Of Stockholders' Equity - 9 months ended Sep. 30, 2016 - USD ($) $ in Thousands	Total	Common Stock	Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Balance - December 31, 2015 at Dec. 31, 2015	$ 438,575	$ 270	$ 166,566	$ 301,206	$ 0	$ (29,467)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	103,372			103,372
Issuance of 269,287 shares of common stock pursuant to stock-based awards, net of shares tendered for payment of taxes	(3,231)	3	(3,234)
Income tax benefit relating to issuance of common stock pursuant to stock-based awards	3,640		3,640
Stock-based compensation expense	11,421		11,421
Issuance of 4,784 deferred stock units relating to prior year compensation	264		264
Other comprehensive loss	(595)				(595)
Cash dividends ($0.90 per share)	(22,078)			(22,078)
Dividend equivalents on stock-based awards			777	(777)
Balance - September 30, 2016 at Sep. 30, 2016	$ 531,368	$ 273	$ 179,434	$ 381,723	$ (595)	$ (29,467)