Business Combinations - Schedule of Aggregate Purchase Consideration and Allocation (Details) $ / shares in Units, shares in Thousands, $ in Thousands	Jul. 17, 2025 USD ($) $ / shares shares	Oct. 31, 2025 USD ($) shares	Oct. 31, 2024 USD ($) shares	Oct. 31, 2023 USD ($)
Allocations
Goodwill		$ 26,899,215	$ 3,448,850	$ 3,346,065
Common stock, shares outstanding (in shares) | shares		185,994	154,112
Share price (in USD per share) | $ / shares	$ 571.20
Ansys, Inc
Allocations
Common stock, shares outstanding (in shares) | shares	88,100
Ansys, Inc
Business Combination, Contingent Consideration [Line Items]
Cash for outstanding Ansys Common Stock	$ 17,613,185
Fair value of Synopsys Common Stock issued for outstanding Ansys Common Stock	17,100,000
Fair value of assumed Ansys equity awards attributable to pre-combination services	130,963
Settlement of pre-existing relationships	8,794
Total purchase consideration	34,858,480
Less: cash acquired	(931,740)
Total purchase consideration, net of cash acquired	33,926,740
Allocations
Total current assets	898,127
Property and equipment	106,209
Goodwill	23,442,889
Intangible assets	12,990,000
Other long-term assets	253,815
Deferred revenue	(637,076)
Other current liabilities	(303,526)
Long-term deferred revenue	(34,070)
Long-term deferred tax liabilities	(2,624,094)
Other long-term liabilities	(165,534)
Total purchase consideration allocation	$ 33,926,740
Business acquisition, share price (in USD per share) | $ / shares	$ 199.91
Business acquisition, exchange ratio	0.3399
Ansys, Inc | Common Stock
Business Combination, Contingent Consideration [Line Items]
Fair value of Synopsys Common Stock issued for outstanding Ansys Common Stock	$ 17,105,538
Allocations
Stock issued for acquisition (in shares) | shares	30,000