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, 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	0		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)
Other comprehensive income (loss)	(5,044)				(5,044)
Cash dividends	(59,270)			(59,270)
Dividend equivalents on stock-based awards	0		1,291	(1,291)
Ending Balance at Dec. 31, 2018	706,255	280	203,246	563,496	(2,605)	(58,162)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	146,509			146,509
Issuance of common stock pursuant to stock-based awards, net of shares tendered for payment of taxes	(8,084)	1	(8,085)
Stock-based compensation expense	16,077		16,077
Repurchases of common stock	(28,700)
Other comprehensive income (loss)	3,728				3,728
Cash dividends	(63,813)			(63,813)
Dividend equivalents on stock-based awards	0		1,247	(1,247)
Ending Balance at Dec. 31, 2019	$ 800,672	$ 281	$ 212,485	$ 644,945	$ 1,123	$ (58,162)