Consolidated Statement Of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss) Income	Treasury Stock
Beginning Balance at Dec. 31, 2015	$ 438,575	$ 270	$ 166,566	$ 301,206		$ (29,467)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	129,671			129,671
Issuance of common stock pursuant to stock-based awards, net of shares tendered for payment of taxes	(5,409)	4	(5,413)
Income tax benefit relating to issuance of common stock pursuant to stock-based awards	7,983		7,983
Stock-based compensation expense	15,420		15,420
Issuance of deferred stock units relating to prior year compensation	264		264
Cash dividends	(34,437)			(34,437)
Dividend equivalents on stock-based awards			1,161	(1,161)
Ending Balance at Dec. 31, 2016	550,269	274	185,981	395,279	$ (1,798)	(29,467)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	132,884			132,884
Issuance of common stock pursuant to stock-based awards, net of shares tendered for payment of taxes	(10,531)	3	(10,534)
Stock-based compensation expense	20,036		20,036
Issuance of deferred stock units relating to prior year compensation	6,907		6,907
Other comprehensive income (loss)	4,237				4,237
Cash dividends	(51,057)			(51,057)
Dividend equivalents on stock-based awards			1,600	(1,600)
Ending Balance at Dec. 31, 2017	652,745	277	203,990	475,506	2,439	(29,467)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	148,551			148,551
Issuance of common stock pursuant to stock-based awards, net of shares tendered for payment of taxes	(16,097)	3	(16,100)
Stock-based compensation expense	14,065		14,065
Repurchases of common stock	(28,695)					(28,695)
Other comprehensive income (loss)	(5,044)				(5,044)
Cash dividends	(59,270)			(59,270)
Dividend equivalents on stock-based awards			1,291	(1,291)
Ending Balance at Dec. 31, 2018	$ 706,255	$ 280	$ 203,246	$ 563,496	$ (2,605)	$ (58,162)