Separate Financial Information of Guarantor Subsidiaries - Condensed Consolidating Balance Sheet (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Assets
Cash and cash equivalents	$ 514,151	$ 71,495	$ 77,295	$ 63,759
Trade and other accounts receivable, net	56,429	104,539
Inventory	814,503	952,907
Other current assets	48,014	34,612
Property and equipment, net	315,029	319,628	308,357
Operating lease assets	525,634
Goodwill and other intangible assets, net	598,321	592,837
Other assets	23,066	22,428
Total assets	2,895,147	2,098,446	2,097,414
Liabilities and Stockholders’ Equity (Deficit)
Accounts payable	236,333	278,688
Accrued liabilities	170,665	169,054
Income taxes payable	2,917	8,336
Long-term debt	1,797,077	1,594,543
Operating lease liability	547,642
Other liabilities	32,976	27,757
Deferred income tax liabilities, net	92,094	80,391
Total liabilities	2,879,704	2,158,769
Total stockholders’ equity (deficit)	15,443	(60,323)	(268,556)	(363,616)
Total liabilities and stockholders’ equity (deficit)	2,895,147	2,098,446
Parent
Assets
Other current assets	6,908	1,436
Property and equipment, net	6	6
Investment in subsidiaries	1,756,347	1,621,843
Other assets	1,431	1,446
Total assets	1,764,692	1,624,731
Liabilities and Stockholders’ Equity (Deficit)
Accounts payable	36	48
Due to affiliates	1,742,661	1,672,322
Accrued liabilities	205	188
Income taxes payable	419	6,055
Other liabilities	5,928	6,441
Total liabilities	1,749,249	1,685,054
Total stockholders’ equity (deficit)	15,443	(60,323)
Total liabilities and stockholders’ equity (deficit)	1,764,692	1,624,731
Sally Holdings and Sally Capital
Assets
Cash and cash equivalents	194,622	10	10	10
Other current assets	132	132
Investment in subsidiaries	4,582,915	4,374,334
Other assets	3,104	3,499
Total assets	4,780,773	4,377,975
Liabilities and Stockholders’ Equity (Deficit)
Due to affiliates	1,196,746	1,142,324
Accrued liabilities	29,165	17,937
Income taxes payable	2,302	2,161
Long-term debt	1,796,213	1,593,710
Total liabilities	3,024,426	2,756,132
Total stockholders’ equity (deficit)	1,756,347	1,621,843
Total liabilities and stockholders’ equity (deficit)	4,780,773	4,377,975
Guarantor Subsidiaries
Assets
Cash and cash equivalents	217,865	41,009	29,050	22,090
Trade and other accounts receivable, net	29,637	65,746
Due from affiliates	3,015,299	2,878,072
Inventory	615,092	722,830
Other current assets	26,103	22,480
Property and equipment, net	263,381	258,132
Operating lease assets	392,863
Investment in subsidiaries	390,579	385,629
Goodwill and other intangible assets, net	449,802	452,645
Other assets	5,059	(581)
Total assets	5,405,680	4,825,962
Liabilities and Stockholders’ Equity (Deficit)
Accounts payable	183,088	235,940
Accrued liabilities	110,165	121,375
Income taxes payable		1
Long-term debt	2	1
Operating lease liability	413,685
Other liabilities	26,889	17,639
Deferred income tax liabilities, net	88,936	76,672
Total liabilities	822,765	451,628
Total stockholders’ equity (deficit)	4,582,915	4,374,334
Total liabilities and stockholders’ equity (deficit)	5,405,680	4,825,962
Non-Guarantor Subsidiaries
Assets
Cash and cash equivalents	101,664	30,476	$ 48,235	$ 41,659
Trade and other accounts receivable, net	26,792	38,793
Inventory	199,411	230,077
Other current assets	14,871	10,564
Property and equipment, net	51,642	61,490
Operating lease assets	132,771
Goodwill and other intangible assets, net	148,519	140,192
Other assets	13,472	18,064
Total assets	689,142	529,656
Liabilities and Stockholders’ Equity (Deficit)
Accounts payable	53,209	42,700
Due to affiliates	75,892	63,426
Accrued liabilities	31,130	29,554
Income taxes payable	196	119
Long-term debt	862	832
Operating lease liability	133,957
Other liabilities	159	3,677
Deferred income tax liabilities, net	3,158	3,719
Total liabilities	298,563	144,027
Total stockholders’ equity (deficit)	390,579	385,629
Total liabilities and stockholders’ equity (deficit)	689,142	529,656
Consolidating Eliminations
Assets
Due from affiliates	(3,015,299)	(2,878,072)
Investment in subsidiaries	(6,729,841)	(6,381,806)
Total assets	(9,745,140)	(9,259,878)
Liabilities and Stockholders’ Equity (Deficit)
Due to affiliates	(3,015,299)	(2,878,072)
Total liabilities	(3,015,299)	(2,878,072)
Total stockholders’ equity (deficit)	(6,729,841)	(6,381,806)
Total liabilities and stockholders’ equity (deficit)	$ (9,745,140)	$ (9,259,878)