Quarterly Statement of Operations Information (Unaudited) - (Detail) - USD ($)	3 Months Ended									12 Months Ended
	Sep. 26, 2020	Jun. 27, 2020	Mar. 28, 2020	Dec. 28, 2019	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 29, 2018	Mar. 31, 2018	Sep. 26, 2020	Sep. 28, 2019	Sep. 29, 2018
Quarterly Financial Information Disclosure [Abstract]
Benefit for income taxes										$ (108,600,000)	$ (54,100,000)	$ (307,300,000)
Goodwill impairment charge									$ 685,700,000	0	0	685,700,000
Impairment of intangible assets and equipment	$ 241,600,000		$ 443,800,000	$ 30,200,000						4,400,000	106,700,000	46,000,000.0
Debt extinguishment losses										0	(800,000)	(45,900,000)
Total revenue	1,347,000,000.0	$ 822,900,000	756,100,000	850,500,000	$ 865,800,000	$ 852,400,000	$ 818,400,000	$ 830,700,000		3,776,400,000	3,367,300,000	3,217,900,000
Gross profit	931,800,000	466,100,000	395,800,000	433,800,000	249,500,000	444,800,000	42,400,000	434,100,000		2,227,500,000	1,170,900,000	1,696,700,000
Net income (loss)	$ 495,000,000.0	$ 137,900,000	$ 96,300,000	$ 386,100,000	$ (123,500,000)	$ 93,900,000	$ (272,600,000)	$ 98,600,000		$ 1,115,200,000	$ (203,600,000)	$ (111,300,000)
Diluted net income per common share (in dollars per share)	$ 1.88	$ 0.53	$ 0.36	$ 1.43	$ (0.46)	$ 0.35	$ (1.01)	$ 0.36		$ 4.21	$ (0.76)	$ (0.40)