Segment Reporting (Summary Of The Operating Information) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 28, 2019	Sep. 30, 2020	Sep. 28, 2019
Segment Reporting Information [Line Items]
Revenues	$ 1,368,673	$ 1,429,428	$ 4,110,763	$ 4,250,366
Costs of revenue	231,889	271,778	698,268	793,655
Operating expenses	941,833	1,068,873	2,892,270	3,038,873
Total costs and expenses	1,173,722	1,340,651	3,590,538	3,832,528
Gain on sale of businesses	216,869	0	216,869	0
Operating earnings (loss)	411,820	88,777	737,094	417,838
Domestic Segment
Segment Reporting Information [Line Items]
Revenues	1,230,769	1,265,263	3,645,397	3,762,205
Costs of revenue	219,938	246,634	638,284	719,119
Operating expenses	566,777	639,590	1,724,545	1,817,244
Total costs and expenses	786,715	886,224	2,362,829	2,536,363
Gain on sale of businesses	0		0
Operating earnings (loss)	444,054	379,039	1,282,568	1,225,842
International Segment [Member]
Segment Reporting Information [Line Items]
Revenues	137,904	164,165	465,366	488,161
Costs of revenue	11,951	25,144	59,984	74,536
Operating expenses	58,626	68,153	182,594	209,580
Total costs and expenses	70,577	93,297	242,578	284,116
Gain on sale of businesses	0		0
Operating earnings (loss)	67,327	70,868	222,788	204,045
Other
Segment Reporting Information [Line Items]
Operating expenses	316,430	361,130	985,131	1,012,049
Total costs and expenses	316,430	361,130	985,131	1,012,049
Gain on sale of businesses	216,869		216,869
Operating earnings (loss)	$ (99,561)	$ (361,130)	$ (768,262)	$ (1,012,049)