Revenue Recognition (Schedule of Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 27, 2019	Jun. 28, 2019	Mar. 29, 2019	Dec. 28, 2018	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Dec. 29, 2017	Sep. 27, 2019	Sep. 28, 2018	Sep. 29, 2017
Revenue from External Customer [Line Items]
Revenue from contract with customer	$ 298,827	$ 302,159	$ 338,258	$ 302,376	$ 240,571	$ 214,780	$ 299,722	$ 299,527	$ 1,241,620	$ 1,054,600
Revenue from contract with customer, percent									100.00%	100.00%
United States
Revenue from External Customer [Line Items]
Revenue from contract with customer									$ 449,203	$ 353,235
Revenue from contract with customer, percent									36.00%	33.00%
International
Revenue from External Customer [Line Items]
Revenue from contract with customer									$ 792,417	$ 701,365
Revenue from contract with customer, percent									64.00%	67.00%
Licensing
Revenue from External Customer [Line Items]
Revenue from contract with customer	$ 264,796	$ 271,897	$ 310,308	$ 260,279	$ 214,699	$ 183,771	$ 272,135	$ 270,172	$ 1,107,280	$ 940,777	$ 965,864
Revenue from contract with customer, percent									89.00%	89.00%
Revenue from contract with customer, licensing percent									100.00%	100.00%
Products and services
Revenue from External Customer [Line Items]
Revenue from contract with customer									$ 134,340	$ 113,823	$ 114,313
Revenue from contract with customer, percent									11.00%	11.00%
Broadcast
Revenue from External Customer [Line Items]
Revenue from contract with customer									$ 474,147	$ 385,705
Revenue from contract with customer, licensing percent									43.00%	41.00%	44.00%
Mobile
Revenue from External Customer [Line Items]
Revenue from contract with customer									$ 193,052	$ 148,356
Revenue from contract with customer, licensing percent									17.00%	16.00%	15.00%
CE
Revenue from External Customer [Line Items]
Revenue from contract with customer									$ 154,399	$ 144,132
Revenue from contract with customer, licensing percent									14.00%	15.00%	13.00%
PC
Revenue from External Customer [Line Items]
Revenue from contract with customer									$ 113,597	$ 106,765
Revenue from contract with customer, licensing percent									10.00%	11.00%	13.00%
Other
Revenue from External Customer [Line Items]
Revenue from contract with customer									$ 172,085	$ 155,819
Revenue from contract with customer, licensing percent									16.00%	17.00%	15.00%