Revenue Recognition (Schedule of Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 25, 2020
Revenue from External Customer [Line Items]
Revenue from contract with customer	$ 351,633	$ 389,874
Revenue from contract with customer, percent	100.00%	100.00%
United States
Revenue from External Customer [Line Items]
Revenue from contract with customer	$ 123,922	$ 101,074
Revenue from contract with customer, percent	35.00%	26.00%
International
Revenue from External Customer [Line Items]
Revenue from contract with customer	$ 227,711	$ 288,800
Revenue from contract with customer, percent	65.00%	74.00%
Licensing
Revenue from External Customer [Line Items]
Revenue from contract with customer	$ 332,284	$ 373,005
Revenue from contract with customer, licensing percent	100.00%	100.00%
Revenue from contract with customer, percent	94.00%	96.00%
Products and services
Revenue from External Customer [Line Items]
Revenue from contract with customer	$ 19,349	$ 16,869
Revenue from contract with customer, percent	6.00%	4.00%
Broadcast
Revenue from External Customer [Line Items]
Revenue from contract with customer	$ 121,633	$ 139,300
Revenue from contract with customer, licensing percent	37.00%	37.00%
PC
Revenue from External Customer [Line Items]
Revenue from contract with customer	$ 34,777	$ 32,735
Revenue from contract with customer, licensing percent	10.00%	9.00%
Mobile
Revenue from External Customer [Line Items]
Revenue from contract with customer	$ 74,920	$ 105,623
Revenue from contract with customer, licensing percent	23.00%	28.00%
CE
Revenue from External Customer [Line Items]
Revenue from contract with customer	$ 57,573	$ 51,921
Revenue from contract with customer, licensing percent	17.00%	14.00%
Other
Revenue from External Customer [Line Items]
Revenue from contract with customer	$ 43,381	$ 43,426
Revenue from contract with customer, licensing percent	13.00%	12.00%