Revenue (Details)	3 Months Ended			9 Months Ended
	Sep. 28, 2019		Sep. 29, 2018	Sep. 28, 2019		Sep. 29, 2018
Revenue from External Customer [Line Items]
Percentage of product and maintenance revenue by product group	100.00%		100.00%	100.00%		100.00%
Functional Verification, including Emulation and Prototyping Hardware [Member]
Revenue from External Customer [Line Items]
Percentage of product and maintenance revenue by product group	20.00%	[1]	22.00%	22.00%	[1]	24.00%
Digital IC Design and Signoff [Member]
Revenue from External Customer [Line Items]
Percentage of product and maintenance revenue by product group	30.00%		30.00%	30.00%		29.00%
Custom IC Design and Simulation [Member]
Revenue from External Customer [Line Items]
Percentage of product and maintenance revenue by product group	26.00%		26.00%	26.00%		26.00%
System Interconnect and Analysis [Member]
Revenue from External Customer [Line Items]
Percentage of product and maintenance revenue by product group	9.00%		9.00%	9.00%		9.00%
IP [Member]
Revenue from External Customer [Line Items]
Percentage of product and maintenance revenue by product group	15.00%		13.00%	13.00%		12.00%

[1] ¹ Includes immaterial amount of revenue accounted for under Topic 842.