Consolidating Condensed Financial Information of Guarantor Subsidiaries - Consolidating Condensed Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 30, 2017	Sep. 30, 2017	Dec. 24, 2016	Sep. 24, 2016
ASSETS
Cash and cash equivalents	$ 283,466	$ 32,397	$ 6,581	$ 92,982
Restricted cash	12,419	12,645	10,981
Accounts receivable, net	235,075	237,868	192,224
Inventories	440,421	382,101	430,171
Prepaid expenses and other	22,519	18,045	22,399
Total current assets	993,900	683,056	662,356
Land, buildings, improvements and equipment, net	179,230	180,913	169,836
Goodwill	256,275	256,275	230,385
Other long-term assets	187,947	186,662	154,177
Intercompany receivable	0	0	0
Investment in subsidiaries	0	0	0
Total	1,617,352	1,306,906	1,216,754
LIABILITIES AND EQUITY
Accounts payable	124,583	103,283	135,237
Accrued expenses	100,004	116,549	94,494
Current portion of long-term debt	372	375	397
Total current liabilities	224,959	220,207	230,128
Long-term debt	690,964	395,278	395,011
Intercompany payable	0	0	0
Losses in excess of investment in subsidiaries	0	0	0
Other long-term obligations	39,478	54,279	31,659
Total Central Garden & Pet Company shareholders’ equity	661,889	635,686	559,249
Noncontrolling interest	62	1,456	707
Total equity	661,951	637,142	559,956	554,587
Total	1,617,352	1,306,906	1,216,754
Eliminations
ASSETS
Cash and cash equivalents	0	0	0	0
Restricted cash	0	0	0
Accounts receivable, net	0	0	0
Inventories	0	0	0
Prepaid expenses and other	0	0	0
Total current assets	0	0	0
Land, buildings, improvements and equipment, net	0	0	0
Goodwill	0	0	0
Other long-term assets	(13,578)	(23,801)	(23,226)
Intercompany receivable	(716,935)	(698,743)	(625,147)
Investment in subsidiaries	(1,437,506)	(1,383,633)	(1,251,408)
Total	(2,168,019)	(2,106,177)	(1,899,781)
LIABILITIES AND EQUITY
Accounts payable	0	0	0
Accrued expenses	0	0	0
Current portion of long-term debt	0	0	0
Total current liabilities	0	0	0
Long-term debt	0	0	0
Intercompany payable	(716,935)	(698,743)	(625,147)
Losses in excess of investment in subsidiaries	(29,069)	(19,782)	(21,014)
Other long-term obligations	(13,578)	(23,801)	(23,226)
Total Central Garden & Pet Company shareholders’ equity	(1,408,437)	(1,363,851)	(1,230,394)
Noncontrolling interest	0	0	0
Total equity	(1,408,437)	(1,363,851)	(1,230,394)
Total	(2,168,019)	(2,106,177)	(1,899,781)
Parent | Reportable Legal Entities
ASSETS
Cash and cash equivalents	277,608	19,238	1,772	82,158
Restricted cash	12,419	12,645	10,981
Accounts receivable, net	89,039	78,692	72,850
Inventories	141,788	125,797	137,615
Prepaid expenses and other	6,645	6,059	7,972
Total current assets	527,499	242,431	231,190
Land, buildings, improvements and equipment, net	35,972	38,170	39,384
Goodwill	15,058	15,058	15,058
Other long-term assets	55,752	61,715	44,012
Intercompany receivable	38,956	36,606	38,559
Investment in subsidiaries	1,437,506	1,383,633	1,251,408
Total	2,110,743	1,777,613	1,619,611
LIABILITIES AND EQUITY
Accounts payable	40,775	36,760	46,208
Accrued expenses	45,973	54,909	42,223
Current portion of long-term debt	0	0	22
Total current liabilities	86,748	91,669	88,453
Long-term debt	690,839	395,160	394,564
Intercompany payable	663,241	647,409	575,187
Losses in excess of investment in subsidiaries	0	0	0
Other long-term obligations	8,026	7,689	2,158
Total Central Garden & Pet Company shareholders’ equity	661,889	635,686	559,249
Noncontrolling interest	0	0	0
Total equity	661,889	635,686	559,249
Total	2,110,743	1,777,613	1,619,611
Non- Guarantor Subsidiaries | Reportable Legal Entities
ASSETS
Cash and cash equivalents	5,858	11,693	3,997	9,695
Restricted cash	0	0	0
Accounts receivable, net	5,617	5,586	6,919
Inventories	12,723	9,493	15,435
Prepaid expenses and other	1,059	811	897
Total current assets	25,257	27,583	27,248
Land, buildings, improvements and equipment, net	4,180	4,225	3,858
Goodwill	0	0	0
Other long-term assets	2,032	2,376	3,542
Intercompany receivable	0	0	0
Investment in subsidiaries	0	0	0
Total	31,469	34,184	34,648
LIABILITIES AND EQUITY
Accounts payable	9,241	3,076	7,146
Accrued expenses	2,313	2,391	1,362
Current portion of long-term debt	0	0	0
Total current liabilities	11,554	5,467	8,508
Long-term debt	0	0	0
Intercompany payable	53,694	51,334	49,960
Losses in excess of investment in subsidiaries	0	0	0
Other long-term obligations	0	0	0
Total Central Garden & Pet Company shareholders’ equity	(33,841)	(24,073)	(24,527)
Noncontrolling interest	62	1,456	707
Total equity	(33,779)	(22,617)	(23,820)
Total	31,469	34,184	34,648
Guarantor Subsidiaries | Reportable Legal Entities
ASSETS
Cash and cash equivalents	0	1,466	812	$ 1,129
Restricted cash	0	0	0
Accounts receivable, net	140,419	153,590	112,455
Inventories	285,910	246,811	277,121
Prepaid expenses and other	14,815	11,175	13,530
Total current assets	441,144	413,042	403,918
Land, buildings, improvements and equipment, net	139,078	138,518	126,594
Goodwill	241,217	241,217	215,327
Other long-term assets	143,741	146,372	129,849
Intercompany receivable	677,979	662,137	586,588
Investment in subsidiaries	0	0	0
Total	1,643,159	1,601,286	1,462,276
LIABILITIES AND EQUITY
Accounts payable	74,567	63,447	81,883
Accrued expenses	51,718	59,249	50,909
Current portion of long-term debt	372	375	375
Total current liabilities	126,657	123,071	133,167
Long-term debt	125	118	447
Intercompany payable	0	0	0
Losses in excess of investment in subsidiaries	29,069	19,782	21,014
Other long-term obligations	45,030	70,391	52,727
Total Central Garden & Pet Company shareholders’ equity	1,442,278	1,387,924	1,254,921
Noncontrolling interest	0	0	0
Total equity	1,442,278	1,387,924	1,254,921
Total	$ 1,643,159	$ 1,601,286	$ 1,462,276