CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss) Income	Treasury stock	Total
Balance at Dec. 31, 2019	$ 3,182	$ 4,397,511	$ 5,022,480	$ (32,387)	$ (5,219,505)	$ 4,171,281
Balance (in shares) at Dec. 31, 2019	636,460				(99,762)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation		17,098				17,098
Exercise of stock options	$ 4	13,971				13,975
Exercise of stock options (in shares)	644
Unrealized gain, net on available-for-sale securities				304		304
Repurchase of common stock					$ (579,948)	(579,948)
Repurchase of common stock (in shares)					(10,503)
Foreign currency translation				(30,599)		(30,599)
Net income			278,835			278,835
Balance at Mar. 31, 2020	$ 3,186	4,428,580	5,301,315	(62,682)	$ (5,799,453)	3,870,946
Balance (in shares) at Mar. 31, 2020	637,104				(110,265)
Balance at Dec. 31, 2019	$ 3,182	4,397,511	5,022,480	(32,387)	$ (5,219,505)	4,171,281
Balance (in shares) at Dec. 31, 2019	636,460				(99,762)
Increase (Decrease) in Stockholders' Equity
Net income						590,204
Balance at Jun. 30, 2020	$ 3,190	4,474,379	5,612,684	(53,438)	$ (5,815,275)	4,221,540
Balance (in shares) at Jun. 30, 2020	637,924				(110,563)
Balance at Mar. 31, 2020	$ 3,186	4,428,580	5,301,315	(62,682)	$ (5,799,453)	3,870,946
Balance (in shares) at Mar. 31, 2020	637,104				(110,265)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation		15,936				15,936
Exercise of stock options	$ 4	29,863				29,867
Exercise of stock options (in shares)	820
Unrealized gain, net on available-for-sale securities				200		200
Repurchase of common stock					$ (15,822)	(15,822)
Repurchase of common stock (in shares)					(298)
Foreign currency translation				9,044		9,044
Net income			311,369			311,369
Balance at Jun. 30, 2020	$ 3,190	4,474,379	5,612,684	(53,438)	$ (5,815,275)	4,221,540
Balance (in shares) at Jun. 30, 2020	637,924				(110,563)
Balance at Dec. 31, 2020	$ 3,193	4,537,982	6,432,074	3,034	$ (5,815,423)	5,160,860
Balance (in shares) at Dec. 31, 2020	638,662				(110,565)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation		17,949				17,949
Exercise of stock options	$ 3	6,758				6,761
Exercise of stock options (in shares)	492
Unrealized gain, net on available-for-sale securities				24		24
Repurchase of common stock					$ (13,419)	(13,419)
Repurchase of common stock (in shares)					(150)
Foreign currency translation				(27,932)		(27,932)
Net income			315,194			315,194
Balance at Mar. 31, 2021	$ 3,196	4,562,689	6,747,268	(24,874)	$ (5,828,842)	5,459,437
Balance (in shares) at Mar. 31, 2021	639,154				(110,715)
Balance at Dec. 31, 2020	$ 3,193	4,537,982	6,432,074	3,034	$ (5,815,423)	$ 5,160,860
Balance (in shares) at Dec. 31, 2020	638,662				(110,565)
Increase (Decrease) in Stockholders' Equity
Exercise of stock options (in shares)						570
Net income						$ 718,956
Balance at Jun. 30, 2021	$ 3,198	4,597,333	7,151,030	(16,822)	$ (5,829,241)	5,905,498
Balance (in shares) at Jun. 30, 2021	639,576				(110,719)
Balance at Mar. 31, 2021	$ 3,196	4,562,689	6,747,268	(24,874)	$ (5,828,842)	5,459,437
Balance (in shares) at Mar. 31, 2021	639,154				(110,715)
Increase (Decrease) in Stockholders' Equity
Stock-based compensation		16,921				16,921
Exercise of stock options	$ 2	17,723				17,725
Exercise of stock options (in shares)	422
Unrealized loss, net on available-for-sale securities				(183)		(183)
Repurchase of common stock					$ (399)	(399)
Repurchase of common stock (in shares)					(4)
Foreign currency translation				8,235		8,235
Net income			403,762			403,762
Balance at Jun. 30, 2021	$ 3,198	$ 4,597,333	$ 7,151,030	$ (16,822)	$ (5,829,241)	$ 5,905,498
Balance (in shares) at Jun. 30, 2021	639,576				(110,719)