Unaudited Condensed Consolidated Statements of Stockholders' Equity Statement - USD ($) shares in Thousands, $ in Thousands	Total		Cumulative Effect, Period of Adoption, Adjustment [Member]	Common Stock	Capital in Excess of Par Value	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment [Member]	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Total  Synopsys Stockholders’ Equity	Non-controlling Interest
Balance (in shares) at Oct. 31, 2019				150,331
Beginning balance at Oct. 31, 2019	$ 4,088,876			$ 1,503	$ 1,635,455	$ 3,164,144		$ (625,642)	$ (92,447)	$ 4,083,013	$ 5,863
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	466,421					466,892				466,892	(471)
Other comprehensive income (loss), net of tax effects	$ 19,627								19,627	19,627
Purchases of treasury stock (in shares)	(1,380)	[1]		(1,380)
Purchases of treasury stock	$ (200,000)	[1]		$ (12)	12			(200,000)		(200,000)
Common stock issued, net of shares withheld for employee taxes (in shares)	2,807	[1]		2,807
Common stock issued, net of shares withheld for employee taxes	$ 56,238			$ 28	(182,036)	(33,092)		271,338		56,238
Stock-based compensation	170,155				170,155					170,155
Balance (in shares) at Jul. 31, 2020				151,758
Ending balance at Jul. 31, 2020	4,601,317			$ 1,519	1,623,586	3,597,944		(554,304)	(72,820)	4,595,925	5,392
Balance (in shares) at Apr. 30, 2020				150,908
Beginning balance at Apr. 30, 2020	4,280,949			$ 1,509	1,655,787	3,356,489		(634,669)	(104,030)	4,275,086	5,863
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	252,440					252,911				252,911	(471)
Other comprehensive income (loss), net of tax effects	$ 31,210								31,210	31,210
Purchases of treasury stock (in shares)	(149)	[1]		(149)
Purchases of treasury stock	$ (20,000)	[1]						(20,000)		(20,000)
Equity forward contract	$ 20,000				20,000					20,000
Common stock issued, net of shares withheld for employee taxes (in shares)	999	[1]		999
Common stock issued, net of shares withheld for employee taxes	$ (25,119)			$ 10	(114,038)	(11,456)		100,365		(25,119)
Stock-based compensation	61,837				61,837					61,837
Balance (in shares) at Jul. 31, 2020				151,758
Ending balance at Jul. 31, 2020	4,601,317			$ 1,519	1,623,586	3,597,944		(554,304)	(72,820)	4,595,925	5,392
Balance (in shares) at Oct. 31, 2020				152,618
Beginning balance at Oct. 31, 2020	4,912,367			$ 1,528	1,653,166	3,795,397		(488,613)	(54,074)	4,907,404	4,963
Beginning balance (Retained earnings adjustment due to adoption of ASC 326) at Oct. 31, 2020			$ (3,200)				$ (3,200)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	555,222					556,069				556,069	(847)
Other comprehensive income (loss), net of tax effects	$ 5,663								5,663	5,663
Purchases of treasury stock (in shares)	(2,114)			(2,114)
Purchases of treasury stock	$ (538,082)			$ (21)	21			(538,082)		(538,082)
Equity forward contract	$ (35,000)				(35,000)					(35,000)
Common stock issued, net of shares withheld for employee taxes (in shares)	2,093			2,093
Common stock issued, net of shares withheld for employee taxes	$ 9,636			$ 19	(259,737)			269,354		9,636
Stock-based compensation	248,530				248,530					248,530
Balance (in shares) at Jul. 31, 2021				152,597
Ending balance at Jul. 31, 2021	5,155,136			$ 1,526	1,606,980	4,348,266		(757,341)	(48,411)	5,151,020	4,116
Balance (in shares) at Apr. 30, 2021				152,554
Beginning balance at Apr. 30, 2021	5,092,505			$ 1,526	1,679,801	4,149,620		(701,457)	(41,355)	5,088,135	4,370
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	198,392					198,646				198,646	(254)
Other comprehensive income (loss), net of tax effects	$ (7,056)								(7,056)	(7,056)
Purchases of treasury stock (in shares)	(521)	[2]		(521)
Purchases of treasury stock	$ (140,000)	[2]		$ (5)	5			(140,000)		(140,000)
Equity forward contract	$ (35,000)				(35,000)					(35,000)
Common stock issued, net of shares withheld for employee taxes (in shares)	564	[2]		564
Common stock issued, net of shares withheld for employee taxes	$ (38,867)			$ 5	(122,988)			84,116		(38,867)
Stock-based compensation	85,162				85,162					85,162
Balance (in shares) at Jul. 31, 2021				152,597
Ending balance at Jul. 31, 2021	$ 5,155,136			$ 1,526	$ 1,606,980	$ 4,348,266		$ (757,341)	$ (48,411)	$ 5,151,020	$ 4,116

[1] The third quarter of fiscal 2020 includes the settlement of the 148,953 shares and $20.0 million equity forward contract from the February 2020 ASR settled in May 2020.

[2] Does not include the 99,573 shares and $35.0 million equity forward contract from the June 2021 ASR.