Unaudited Condensed Consolidated Statements of Stockholders' Equity Statement - USD ($) shares in Thousands, $ in Thousands	Total		Common Stock	Capital in Excess of Par Value	Retained Earnings		Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Total Synopsys Stockholders’ Equity	Non-controlling Interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect adjustment | Accounting Standards Update 2014-09	$ 257,594				$ 257,594	[1]			$ 257,594
Cumulative effect adjustment | Accounting Standards Update 2018-02	(130,544)				(130,544)	[2]			(130,544)
Balance (in shares) at Oct. 31, 2018			149,265
Beginning balance at Oct. 31, 2018	3,485,015		$ 1,493	$ 1,644,830	2,543,688		$ (597,682)	$ (113,177)	3,479,152	$ 5,863
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	371,653				371,653				371,653
Other comprehensive income (loss), net of tax effects	$ 16,524							16,524	16,524
Purchases of treasury stock (in shares)	(1,901)	[3],[4]	(1,901)
Purchases of treasury stock, value	$ (209,185)	[3],[4]	$ (19)	19			(209,185)		(209,185)
Equity forward contract	$ (20,000)			(20,000)					(20,000)
Common stock issued, net of shares withheld for employee taxes (in shares)	3,009	[3],[4]	3,009
Common stock issued, net of shares withheld for employee taxes	$ 54,991		$ 30	(140,841)	(38,961)		234,763		54,991
Stock-based compensation	113,621			113,621					113,621
Balance (in shares) at Jul. 31, 2019			150,373
Ending balance at Jul. 31, 2019	3,939,669		$ 1,504	1,597,629	3,003,430		(572,104)	(96,653)	3,933,806	5,863
Balance (in shares) at Apr. 30, 2019			149,982
Beginning balance at Apr. 30, 2019	3,915,435		$ 1,500	1,659,484	2,912,811		(567,503)	(96,720)	3,909,572	5,863
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	99,929				99,929				99,929
Other comprehensive income (loss), net of tax effects	$ 67							67	67
Purchases of treasury stock (in shares)	(775)	[3]	(775)
Purchases of treasury stock, value	$ (100,000)	[3]	$ (8)	8			(100,000)		(100,000)
Common stock issued, net of shares withheld for employee taxes (in shares)	1,166	[3]	1,166
Common stock issued, net of shares withheld for employee taxes	$ (15,209)		$ 12	(101,310)	(9,310)		95,399		(15,209)
Stock-based compensation	39,447			39,447					39,447
Balance (in shares) at Jul. 31, 2019			150,373
Ending balance at Jul. 31, 2019	3,939,669		$ 1,504	1,597,629	3,003,430		(572,104)	(96,653)	3,933,806	5,863
Balance (in shares) at Oct. 31, 2019			150,331
Beginning balance at Oct. 31, 2019	4,088,876	[5]	$ 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)	[6]	(1,380)
Purchases of treasury stock, value	$ (200,000)	[6]	$ (12)	12			(200,000)		(200,000)
Common stock issued, net of shares withheld for employee taxes (in shares)	2,807	[6]	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)		(149)
Purchases of treasury stock, value	$ (20,000)						(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		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

[1] See Note 2. Summary of Significant Accounting Policies in the Company’s Annual Report on Form 10-K for the year ended October 31, 2019 for additional information on the retained earnings adjustment due to adoption of Accounting Standards Codification (ASC) 606 and ASC 340, “Other Assets and Deferred Costs”.

[2] See Note 11. Income Taxes in the Company’s Annual Report on Form 10-K for the year ended October 31, 2019 for additional information on the retained earnings adjustment due to adoption of Accounting Standard Update (ASU) 2016-16.

[3] Does not include the 90,202 shares or $20.0 million equity forward contract from the June 2019 ASR settled in August 2019.

[4] The third quarter of fiscal 2019 includes the settlement of the 97,601 shares or $20.0 million equity forward contract from the February 2019 ASR settled in May 2019.

[5] Derived from audited financial statements.

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