Consolidated Statements of Stockholders' Equity - 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
Balance (in shares) at Oct. 31, 2015		155,157
Beginning balance at Oct. 31, 2015	$ 3,133,989	$ 1,552	$ 1,610,460	$ 1,725,727	$ (98,375)	$ (105,375)	$ 3,133,989	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	266,826			266,826			266,826
Other comprehensive income (loss), net of tax effects	$ 798					798	798
Purchases of treasury stock (in shares)	(8,506)	(8,506)
Purchases of treasury stock, value	$ (400,000)	$ (85)	20,085		(420,000)		(400,000)
Common stock issued, net of shares withheld for employee taxes (in shares)	4,803	4,803
Common stock issued, net of shares withheld for employee taxes	$ 98,668	$ 48	(80,735)	(44,968)	224,323		98,668
Stock-based compensation	97,583		97,583				97,583
Other	(2,718)		(2,718)				(2,718)
Balance (in shares) at Oct. 31, 2016		151,454
Ending balance at Oct. 31, 2016	3,195,146	$ 1,515	1,644,675	1,947,585	(294,052)	(104,577)	3,195,146	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	136,563			136,563			136,563
Other comprehensive income (loss), net of tax effects	$ 38,598					38,598	38,598
Purchases of treasury stock (in shares)	(5,413)	(5,413)
Purchases of treasury stock, value	$ (380,000)	$ (54)	54		(380,000)		(380,000)
Common stock issued, net of shares withheld for employee taxes (in shares)	4,404	4,404
Common stock issued, net of shares withheld for employee taxes	$ 90,530	$ 44	(110,976)	(46,382)	247,844		90,530
Stock-based compensation	108,294		108,294				108,294
Equity forward contract	(20,000)		(20,000)				(20,000)
Non-controlling interest in an equity investment	4,104							4,104
Balance (in shares) at Oct. 31, 2017		150,445
Ending balance at Oct. 31, 2017	3,279,724	$ 1,505	1,622,429	2,143,873	(426,208)	(65,979)	3,275,620	4,104
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Retained earnings adjustment due to adoption of an accounting standard update | Adjustment related to stock-based compensation	106,489		382	106,107			106,489
Net income	432,518			432,518			432,518
Other comprehensive income (loss), net of tax effects	$ (47,198)					(47,198)	(47,198)
Purchases of treasury stock (in shares)	(4,688)	(4,688)
Purchases of treasury stock, value	$ (420,000)	$ (47)	47		(420,000)		(420,000)
Common stock issued, net of shares withheld for employee taxes (in shares)	3,508	3,508
Common stock issued, net of shares withheld for employee taxes	$ 79,629	$ 35	(136,522)	(32,410)	248,526		79,629
Stock-based compensation	138,876		138,876				138,876
Equity forward contract	20,000		20,000				20,000
Non-controlling interest in an equity investment	1,759							1,759
Balance (in shares) at Oct. 31, 2018		149,265
Ending 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]
Retained earnings adjustment due to adoption of an accounting standard update | Adjustment related to reclassification of certain tax effects from accumulated other comprehensive income	$ (293)			$ (293)			$ (293)