Net Income per Share - Reconciliation of Weighted Average Common Shares Used to Calculate Basic Net Income Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended
		Jan. 31, 2021	Jan. 31, 2020
Numerator:
Net income attributed to Synopsys		$ 162,345	$ 104,061
Denominator:
Weighted-average common shares for basic net income per share (shares)		152,498	150,244
Dilutive effect of potential common shares from equity-based compensation (shares)		4,779	4,260
Weighted-average common shares for diluted net income per share (shares)		157,277	154,504
Net income per share:
Basic (in USD per share)		$ 1.06	$ 0.69
Diluted (in USD per share)		$ 1.03	$ 0.67
Anti-dilutive employee stock-based awards excluded (shares)	[1]	334	414

[1] These stock options and unvested restricted stock units were anti-dilutive for the respective periods and are excluded in calculating diluted net income per share. While such awards were anti-dilutive for the respective periods, they could be dilutive in the future.