Business Segment Data - Financial Information Relating to Company's Business Segments (Detail) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 24, 2016 USD ($) JointVenture	Jun. 25, 2016 USD ($)	Mar. 26, 2016 USD ($)	Dec. 26, 2015 USD ($)	Sep. 26, 2015 USD ($)	Jun. 27, 2015 USD ($)	Mar. 28, 2015 USD ($)	Dec. 27, 2014 USD ($)	Sep. 24, 2016 USD ($) JointVenture	Sep. 26, 2015 USD ($)	Sep. 27, 2014 USD ($)	Dec. 30, 2014 JointVenture
Net sales:
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
Income (loss) from operations:
Operating income (loss)									129,358	91,435	56,213
Interest expense									(42,847)	(40,027)	(42,844)
Interest income									140	129	94
Other income (expense)									(17,013)	13	403
Income before income taxes and noncontrolling interest									69,638	51,550	13,866
Income tax expense									24,053	18,535	4,045
Net income including noncontrolling interest									45,585	33,015	9,821
Net income attributable to noncontrolling interest									1,071	1,044	1,017
Net income attributable to Central Garden & Pet Company	(5,611)	$ 26,030	$ 32,697	$ (8,602)	(4,369)	$ 18,800	$ 23,237	$ (5,697)	44,514	31,971	8,804
Assets:
Total assets	1,212,193				1,131,597				1,212,193	1,131,597	1,148,727
Depreciation and amortization:
Depreciation and amortization									40,001	33,703	35,781
Expenditures for long-lived assets:
Expenditures for long-lived assets									27,622	22,030	17,173
Indefinite-lived intangible assets, impairment charge	1,800				7,300				1,800	7,300
Non-cash impairment charge	$ 16,600								$ 19,367	7,272	5,870
Number of joint ventures | JointVenture	2								2
Purishield LLC and Ceregenin LLC [Member]
Expenditures for long-lived assets:
Non-cash impairment charge									$ 16,600
Number of joint ventures | JointVenture												2
Operating Segments [Member] | Pet Segment [Member]
Net sales:
Net sales									1,081,853	894,549	845,505
Income (loss) from operations:
Operating income (loss)									119,930	98,798	88,077
Assets:
Total assets	$ 508,879				465,171				508,879	465,171	414,279
Depreciation and amortization:
Depreciation and amortization									22,556	15,885	17,256
Expenditures for long-lived assets:
Expenditures for long-lived assets									18,939	17,060	8,561
Indefinite-lived intangible assets, impairment charge									1,800	7,300
Operating Segments [Member] | Garden Segment [Member]
Net sales:
Net sales									747,164	756,188	758,852
Income (loss) from operations:
Operating income (loss)									70,317	60,145	41,020
Assets:
Total assets	304,901				310,981				304,901	310,981	337,461
Depreciation and amortization:
Depreciation and amortization									6,098	5,988	6,793
Expenditures for long-lived assets:
Expenditures for long-lived assets									4,750	2,432	5,541
Charge related to new products											16,900
Gain from sale of manufacturing plant assets											4,900
Corporate [Member]
Income (loss) from operations:
Operating income (loss)									(60,889)	(67,508)	(72,884)
Assets:
Total assets	$ 398,413				$ 355,445				398,413	355,445	396,987
Depreciation and amortization:
Depreciation and amortization									11,347	11,830	11,732
Expenditures for long-lived assets:
Expenditures for long-lived assets									$ 3,933	$ 2,538	$ 3,071