CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Treasury Stock
Beginning balance (in shares) at Dec. 31, 2020		48,148				7,609
Balance at Dec. 31, 2020	$ 1,986,111	$ 481	$ 905,332	$ (46)	$ 1,112,156	$ (31,812)
Increase (Decrease) in Stockholders' Equity
Net income	36,976				36,976
Unrealized loss on available-for-sale securities, net of tax	$ 0
Exercise of stock options and vesting of restricted stock units (in shares)	120					196
Exercise of stock options and vesting of restricted stock units	$ 18,102		7,921			$ 10,181
Employee taxes paid for withheld shares upon equity award settlement (in shares)						(19)
Employee taxes paid for withheld shares upon equity award settlement	(8,958)					$ (8,958)
Stock compensation	$ 25,724		25,724
Issuance of shares pursuant to employee stock purchase plan (in shares)	8					8
Issuance of shares pursuant to employee stock purchase plan	$ 3,038		2,983			$ 55
Ending balance (in shares) at Mar. 31, 2021		48,148				7,424
Balance at Mar. 31, 2021	2,060,993	$ 481	941,960	(46)	1,149,132	$ (30,534)
Beginning balance (in shares) at Dec. 31, 2021		48,148				6,833
Balance at Dec. 31, 2021	2,324,032	$ 481	1,075,650	(46)	1,273,614	$ (25,667)
Increase (Decrease) in Stockholders' Equity
Net income	39,984				39,984
Unrealized loss on available-for-sale securities, net of tax	$ (697)			(697)
Exercise of stock options and vesting of restricted stock units (in shares)	50					157
Exercise of stock options and vesting of restricted stock units	$ 8,045		(5,609)			$ 13,654
Employee taxes paid for withheld shares upon equity award settlement (in shares)						(29)
Employee taxes paid for withheld shares upon equity award settlement	(12,587)					$ (12,587)
Stock compensation	$ 25,279		25,279
Issuance of shares pursuant to employee stock purchase plan (in shares)	8					8
Issuance of shares pursuant to employee stock purchase plan	$ 3,678		3,613			$ 65
Ending balance (in shares) at Mar. 31, 2022		48,148				6,697
Balance at Mar. 31, 2022	$ 2,387,734	$ 481	$ 1,098,933	$ (743)	$ 1,313,598	$ (24,535)