Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock Including Additional Paid in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Dec. 31, 2018	42,505
Balance at Dec. 31, 2018	$ 450,908	$ 194,728	$ (5,543)	$ 640,093
Net income	0	108,839	0	108,839
Other comprehensive income	0	0	67	67
Dividends and dividend equivalents declared	$ 0	(74,117)	0	(74,117)
Common stock issued under the employee equity incentive plan (in shares)	1,083
Common stock issued under the employee equity incentive plan	$ 16,650	0	0	16,650
Common stock issued under the employee stock purchase plan (in shares)	28
Common stock issued under the employee stock purchase plan	$ 3,277	0	0	3,277
Stock-based compensation expense	$ 78,682	0	0	78,682
Balance (in shares) at Dec. 31, 2019	43,616
Balance at Dec. 31, 2019	$ 549,517	229,450	(5,476)	773,491
Net income	0	164,375	0	164,375
Other comprehensive income	0	0	15,616	15,616
Dividends and dividend equivalents declared	$ 0	(95,079)	0	(95,079)
Common stock issued under the employee equity incentive plan (in shares)	1,623
Common stock issued under the employee equity incentive plan	$ 18,767	0	0	18,767
Common stock issued under the employee stock purchase plan (in shares)	28
Common stock issued under the employee stock purchase plan	$ 3,819	0	0	3,819
Stock-based compensation expense	$ 85,598	0	0	$ 85,598
Balance (in shares) at Dec. 31, 2020	45,267			45,267
Balance at Dec. 31, 2020	$ 657,701	298,746	10,140	$ 966,587
Net income	0	242,023	0	242,023
Other comprehensive income	0	0	5,740	5,740
Dividends and dividend equivalents declared	$ 0	(115,890)	0	(115,890)
Common stock issued under the employee equity incentive plan (in shares)	972
Common stock issued under the employee equity incentive plan	$ 17,322	0	0	17,322
Common stock issued under the employee stock purchase plan (in shares)	17
Common stock issued under the employee stock purchase plan	$ 4,670	0	0	4,670
Stock-based compensation expense	$ 123,533	0	0	$ 123,533
Balance (in shares) at Dec. 31, 2021	46,256			46,256
Balance at Dec. 31, 2021	$ 803,226	$ 424,879	$ 15,880	$ 1,243,985