Business Segment Data - Class of Similar Products Which Represented Approximately 10% or More of Company's Consolidated Net Sales (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 24, 2016	Jun. 25, 2016	Mar. 26, 2016	Dec. 26, 2015	Sep. 26, 2015	Jun. 27, 2015	Mar. 28, 2015	Dec. 27, 2014	Sep. 24, 2016	Sep. 26, 2015	Sep. 27, 2014
Revenue from External Customer [Line Items]
Net sales	$ 413,412	$ 514,544	$ 541,249	$ 359,812	$ 386,369	$ 459,446	$ 497,602	$ 307,320	$ 1,829,017	$ 1,650,737	$ 1,604,357
Other pet products [Member]
Revenue from External Customer [Line Items]
Net sales									689,300	594,700	774,200
Garden controls and fertilizer products [Member]
Revenue from External Customer [Line Items]
Net sales									298,800	286,300	262,500
Wild bird feed [Member]
Revenue from External Customer [Line Items]
Net sales									183,600	193,200	202,100
Grass seed [Member]
Revenue from External Customer [Line Items]
Net sales											183,100
Other garden supplies [Member]
Revenue from External Customer [Line Items]
Net sales									331,300	343,500	$ 182,500
Dog and cat products [Member]
Revenue from External Customer [Line Items]
Net sales									$ 326,000	$ 233,000