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	Total  Synopsys Stockholders’ Equity Cumulative Effect, Period of Adoption, Adjustment [Member]	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		104,061					104,061				104,061
Other comprehensive income (loss), net of tax effects		$ 9,136								9,136	9,136
Purchases of treasury stock (in shares)		(579)			(579)
Purchases of treasury stock		$ (80,000)			$ (6)	6			(80,000)		(80,000)
Equity forward contract		$ (20,000)				(20,000)					(20,000)
Common stock issued, net of shares withheld for employee taxes (in shares)		450			450
Common stock issued, net of shares withheld for employee taxes		$ 734			$ 5	(40,561)			41,290		734
Stock-based compensation		51,883				51,883					51,883
Balance (in shares) at Jan. 31, 2020					150,202
Ending balance at Jan. 31, 2020		4,154,690			$ 1,502	1,626,783	3,268,205		(664,352)	(83,311)	4,148,827		5,863
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	[1]			$ (3,200)				$ (3,200)				$ (3,200)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		162,028					162,345				162,345		(317)
Other comprehensive income (loss), net of tax effects		$ 19,299								19,299	19,299
Purchases of treasury stock (in shares)		(837)	[2]		(837)
Purchases of treasury stock		$ (202,871)	[2]		$ (8)	8			(202,871)		(202,871)
Equity forward contract		$ (50,000)				(50,000)					(50,000)
Common stock issued, net of shares withheld for employee taxes (in shares)		583	[2]		583
Common stock issued, net of shares withheld for employee taxes		$ (34,507)			$ 6	(97,781)			63,268		(34,507)
Stock-based compensation		83,782				83,782					83,782
Balance (in shares) at Jan. 31, 2021					152,364
Ending balance at Jan. 31, 2021		$ 4,886,898			$ 1,526	$ 1,589,175	$ 3,954,542		$ (628,216)	$ (34,775)	$ 4,882,252		$ 4,646

[1] In June 2016, the Financial Accounting Standards Board (FASB) issued ASC 326, "Measurement of Credit Losses on Financial Instruments", which replaces the incurred loss methodology with an expected loss methodology. The Company adopted the new standard at the beginning of fiscal 2021.

[2] Does not include the $50.0 million equity forward contract, from the December 2020 ASR.