Segment Information - Financial Information Relating to Company's Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 26, 2016	Mar. 28, 2015	Mar. 26, 2016	Mar. 28, 2015	Sep. 26, 2015
Net sales:
Net sales	$ 541,249	$ 497,602	$ 901,061	$ 804,922
Income (loss) from operations:
Income from operations	59,403	49,971	68,176	51,109
Interest expense - net	(7,087)	(11,858)	(29,210)	(22,290)
Other expense	(88)	(121)	(561)	(489)
Income tax expense	18,793	14,012	13,593	10,043
Income including noncontrolling interest	33,435	23,980	24,812	18,287
Net income attributable to noncontrolling interest	738	743	717	747
Net income attributable to Central Garden & Pet Company	32,697	23,237	24,095	17,540
Depreciation and amortization:
Depreciation and amortization	9,169	8,350	18,202	16,814
Assets:
Total assets	1,323,099	1,269,197	1,323,099	1,269,197	$ 1,131,597
Goodwill (included in corporate assets above):
Goodwill	213,753	209,089	213,753	209,089	209,089
Operating Segments
Goodwill (included in corporate assets above):
Goodwill	213,753	209,089	213,753	209,089	209,089
Operating Segments | Pet segment
Net sales:
Net sales	275,328	221,485	523,990	420,805
Income (loss) from operations:
Income from operations	32,409	27,051	58,604	47,626
Depreciation and amortization:
Depreciation and amortization	4,956	3,878	9,420	7,819
Assets:
Total assets	538,901	450,240	538,901	450,240	465,171
Goodwill (included in corporate assets above):
Goodwill	210,455	209,089	210,455	209,089	209,089
Operating Segments | Garden segment
Net sales:
Net sales	265,921	276,117	377,071	384,117
Income (loss) from operations:
Income from operations	44,407	39,325	41,153	35,790
Depreciation and amortization:
Depreciation and amortization	1,359	1,483	3,044	3,049
Assets:
Total assets	467,026	490,514	467,026	490,514	310,981
Goodwill (included in corporate assets above):
Goodwill	3,298	0	3,298	0	0
Corporate
Income (loss) from operations:
Income from operations	(17,413)	(16,405)	(31,581)	(32,307)
Depreciation and amortization:
Depreciation and amortization	2,854	2,989	5,738	5,946
Assets:
Total assets	$ 317,172	$ 328,443	$ 317,172	$ 328,443	$ 355,445