Condensed Consolidated Statement Of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning balance at Dec. 31, 2019	$ 800,672	$ 281	$ 212,485	$ 644,945	$ 1,123	$ (58,162)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	28,214			28,214
Issuance of shares of common stock pursuant to stock-based awards, net of shares tendered for payment of taxes	(4,517)	1	(4,518)
Stock-based compensation expense	3,295		3,295
Other comprehensive income (loss)	(3,540)				(3,540)
Cash dividends	(16,321)			(16,321)
Dividend equivalents on stock-based awards	0		297	(297)
Ending balance at Mar. 31, 2020	807,803	282	211,559	656,541	(2,417)	(58,162)
Beginning balance at Dec. 31, 2019	800,672	281	212,485	644,945	1,123	(58,162)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	109,747
Ending balance at Sep. 30, 2020	875,562	282	222,257	702,223	8,962	(58,162)
Beginning balance at Mar. 31, 2020	807,803	282	211,559	656,541	(2,417)	(58,162)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	13,186			13,186
Issuance of shares of common stock pursuant to stock-based awards, net of shares tendered for payment of taxes	(99)		(99)
Stock-based compensation expense	4,109		4,109
Other comprehensive income (loss)	7,980				7,980
Cash dividends	(16,349)			(16,349)
Dividend equivalents on stock-based awards	0		295	(295)
Ending balance at Jun. 30, 2020	816,630	282	215,864	653,083	5,563	(58,162)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	68,347			68,347
Issuance of shares of common stock pursuant to stock-based awards, net of shares tendered for payment of taxes	(191)		(191)
Stock-based compensation expense	6,242		6,242
Other comprehensive income (loss)	3,399				3,399
Cash dividends	(18,865)			(18,865)
Dividend equivalents on stock-based awards	0		342	(342)
Ending balance at Sep. 30, 2020	875,562	282	222,257	702,223	8,962	(58,162)
Beginning balance at Dec. 31, 2020	908,326	282	227,407	731,710	7,089	(58,162)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	74,120			74,120
Issuance of shares of common stock pursuant to stock-based awards, net of shares tendered for payment of taxes	(7,767)	1	(7,768)
Stock-based compensation expense	7,436		7,436
Other comprehensive income (loss)	(3,589)				(3,589)
Cash dividends	(18,939)			(18,939)
Dividend equivalents on stock-based awards	0		325	(325)
Ending balance at Mar. 31, 2021	959,587	283	227,400	786,566	3,500	(58,162)
Beginning balance at Dec. 31, 2020	908,326	282	227,407	731,710	7,089	(58,162)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	205,410
Ending balance at Sep. 30, 2021	1,031,140	284	213,271	871,600	4,147	(58,162)
Beginning balance at Mar. 31, 2021	959,587	283	227,400	786,566	3,500	(58,162)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	67,889			67,889
Issuance of shares of common stock pursuant to stock-based awards, net of shares tendered for payment of taxes	(158)	1	(159)
Stock-based compensation expense	6,423		6,423
Purchase of convertible note hedge contracts, net of tax	(75,750)		(75,750)
Issuance of warrants	48,484		48,484
Other comprehensive income (loss)	2,440				2,440
Cash dividends	(22,739)			(22,739)
Dividend equivalents on stock-based awards	0		388	(388)
Ending balance at Jun. 30, 2021	986,176	284	206,786	831,328	5,940	(58,162)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	63,401
Issuance of shares of common stock pursuant to stock-based awards, net of shares tendered for payment of taxes	(333)		(333)
Stock-based compensation expense	6,436		6,436
Other comprehensive income (loss)	(1,793)				(1,793)
Cash dividends	(22,747)			(22,747)
Dividend equivalents on stock-based awards	0		382	(382)
Ending balance at Sep. 30, 2021	$ 1,031,140	$ 284	$ 213,271	$ 871,600	$ 4,147	$ (58,162)