Consolidating Condensed Financial Information of Guarantor Subsidiaries - Consolidating Condensed Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 25, 2017	Mar. 31, 2018	Mar. 25, 2017
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 613,094	$ 569,924	$ 1,055,105	$ 989,422
Cost of goods sold and occupancy	418,637	386,395	728,811	685,215
Gross profit	194,457	183,529	326,294	304,207
Selling, general and administrative expenses	128,671	119,669	237,987	220,409
Operating income	65,786	63,860	88,307	83,798
Interest expense	(10,575)	(6,830)	(17,980)	(13,703)
Interest income	693	8	880	46
Other (expense) income	1,505	(965)	(1,584)	(1,932)
Income before income taxes and noncontrolling interest	57,409	56,073	69,623	68,209
Income tax expense (benefit)	11,643	20,824	(2,593)	25,171
Equity in earnings (losses) of affiliates	0	0	0	0
Income including noncontrolling interest	45,766	35,249	72,216	43,038
Net income attributable to noncontrolling interest	532	565	735	717
Net income attributable to Central Garden & Pet Company	45,234	34,684	71,481	42,321
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net sales	(27,151)	(25,632)	(44,368)	(42,114)
Cost of goods sold and occupancy	(25,495)	(24,006)	(41,667)	(39,440)
Gross profit	(1,656)	(1,626)	(2,701)	(2,674)
Selling, general and administrative expenses	(1,656)	(1,626)	(2,701)	(2,674)
Operating income	0	0	0	0
Interest expense		0	0	0
Interest income		0	0	0
Other (expense) income		0	0	0
Income before income taxes and noncontrolling interest	0	0	0	0
Income tax expense (benefit)		0	0	0
Equity in earnings (losses) of affiliates	(42,113)	(35,988)	(93,059)	(48,621)
Income including noncontrolling interest	(42,113)	(35,988)	(93,059)	(48,621)
Net income attributable to noncontrolling interest	0	0	0	0
Net income attributable to Central Garden & Pet Company	(42,113)	(35,988)	(93,059)	(48,621)
Parent | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net sales	195,464	190,791	354,525	346,309
Cost of goods sold and occupancy	151,868	145,593	277,347	266,729
Gross profit	43,596	45,198	77,178	79,580
Selling, general and administrative expenses	41,677	39,347	78,316	75,312
Operating income	1,919	5,851	(1,138)	4,268
Interest expense	(10,510)	(6,759)	(17,895)	(13,610)
Interest income	692	7	878	45
Other (expense) income	1,108	(737)	(1,810)	(1,340)
Income before income taxes and noncontrolling interest	(6,791)	(1,638)	(19,965)	(10,637)
Income tax expense (benefit)	(13,753)	(718)	672	(3,910)
Equity in earnings (losses) of affiliates	38,272	35,604	92,118	49,048
Income including noncontrolling interest	45,234	34,684	71,481	42,321
Net income attributable to noncontrolling interest	0	0	0	0
Net income attributable to Central Garden & Pet Company	45,234	34,684	71,481	42,321
Non- Guarantor Subsidiaries | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net sales	32,433	26,092	46,176	40,116
Cost of goods sold and occupancy	24,192	20,128	36,008	31,806
Gross profit	8,241	5,964	10,168	8,310
Selling, general and administrative expenses	6,532	4,874	10,437	8,538
Operating income	1,709	1,090	(269)	(228)
Interest expense	(62)	(65)	(78)	(82)
Interest income	1	1	2	1
Other (expense) income	200	(194)	254	(387)
Income before income taxes and noncontrolling interest	1,848	832	(91)	(696)
Income tax expense (benefit)	(1,549)	448	(267)	37
Equity in earnings (losses) of affiliates	0	0	0	0
Income including noncontrolling interest	3,397	384	176	(733)
Net income attributable to noncontrolling interest	532	565	735	717
Net income attributable to Central Garden & Pet Company	2,865	(181)	(559)	(1,450)
Guarantor Subsidiaries | Reportable Legal Entities
Condensed Financial Statements, Captions [Line Items]
Net sales	412,348	378,673	698,772	645,111
Cost of goods sold and occupancy	268,072	244,680	457,123	426,120
Gross profit	144,276	133,993	241,649	218,991
Selling, general and administrative expenses	82,118	77,074	151,935	139,233
Operating income	62,158	56,919	89,714	79,758
Interest expense	(3)	(6)	(7)	(11)
Interest income	0	0	0	0
Other (expense) income	197	(34)	(28)	(205)
Income before income taxes and noncontrolling interest	62,352	56,879	89,679	79,542
Income tax expense (benefit)	26,945	21,094	(2,998)	29,044
Equity in earnings (losses) of affiliates	3,841	384	941	(427)
Income including noncontrolling interest	39,248	36,169	93,618	50,071
Net income attributable to noncontrolling interest	0	0	0	0
Net income attributable to Central Garden & Pet Company	$ 39,248	$ 36,169	$ 93,618	$ 50,071