Separate Financial Information of Guarantor Subsidiaries - Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Condensed Cash Flow Statements Captions [Line Items]
Net cash provided (used) by operating activities	$ 426,889	$ 320,415	$ 372,661
Cash Flows from Investing Activities:
Payments for property and equipment, net	(110,805)	(92,443)	(86,138)
Acquisitions, net of cash acquired	(12,970)	(3,424)	(9,175)
Net cash used by investing activities	(123,775)	(95,867)	(95,313)
Cash Flows from Financing Activities:
Proceeds from issuance of long-term debt	1,087,504	593,504	461,819
Repayments of long-term debt	(882,921)	(777,538)	(558,599)
Debt issuance costs	(6,257)		(1,151)
Payments for common stock repurchased	(61,357)	(47,434)	(166,701)
Proceeds from exercises of stock options	2,792	2,160	1,350
Net cash provided (used) by financing activities	139,761	(229,308)	(263,282)
Effect of foreign exchange rate changes on cash and cash equivalents	(219)	(1,040)	(530)
Net increase (decrease) in cash and cash equivalents	442,656	(5,800)	13,536
Cash and cash equivalents, beginning of period	71,495	77,295	63,759
Cash and cash equivalents, end of period	514,151	71,495	77,295
Parent
Condensed Cash Flow Statements Captions [Line Items]
Net cash provided (used) by operating activities	(11,769)	2,364	23,424
Cash Flows from Investing Activities:
Payments for property and equipment, net	(5)	(1)
Net cash used by investing activities	(5)	(1)
Cash Flows from Financing Activities:
Payments for common stock repurchased	(61,357)	(47,434)	(166,701)
Proceeds from exercises of stock options	2,792	2,160	1,350
Due to affiliates	70,339	42,911	141,927
Net cash provided (used) by financing activities	11,774	(2,363)	(23,424)
Sally Holdings and Sally Capital
Condensed Cash Flow Statements Captions [Line Items]
Net cash provided (used) by operating activities	(58,166)	(70,150)	(62,948)
Cash Flows from Financing Activities:
Proceeds from issuance of long-term debt	1,087,500	593,500	461,814
Repayments of long-term debt	(882,887)	(777,533)	(558,000)
Debt issuance costs	(6,257)		(1,151)
Due to affiliates	54,422	254,183	160,285
Net cash provided (used) by financing activities	252,778	70,150	62,948
Net increase (decrease) in cash and cash equivalents	194,612
Cash and cash equivalents, beginning of period	10	10	10
Cash and cash equivalents, end of period	194,622	10	10
Guarantor Subsidiaries
Condensed Cash Flow Statements Captions [Line Items]
Net cash provided (used) by operating activities	417,940	373,313	384,958
Cash Flows from Investing Activities:
Payments for property and equipment, net	(98,379)	(79,379)	(68,689)
Acquisitions, net of cash acquired	(5,479)	(2,584)
Due from affiliates	(137,227)	(279,391)	(309,310)
Net cash used by investing activities	(241,085)	(361,354)	(377,999)
Cash Flows from Financing Activities:
Proceeds from issuance of long-term debt	4	4	5
Repayments of long-term debt	(3)	(4)	(4)
Net cash provided (used) by financing activities	1		1
Net increase (decrease) in cash and cash equivalents	176,856	11,959	6,960
Cash and cash equivalents, beginning of period	41,009	29,050	22,090
Cash and cash equivalents, end of period	217,865	41,009	29,050
Non-Guarantor Subsidiaries
Condensed Cash Flow Statements Captions [Line Items]
Net cash provided (used) by operating activities	78,884	14,888	27,227
Cash Flows from Investing Activities:
Payments for property and equipment, net	(12,421)	(13,063)	(17,449)
Acquisitions, net of cash acquired	(7,491)	(840)	(9,175)
Net cash used by investing activities	(19,912)	(13,903)	(26,624)
Cash Flows from Financing Activities:
Repayments of long-term debt	(31)	(1)	(595)
Due to affiliates	12,466	(17,703)	7,098
Net cash provided (used) by financing activities	12,435	(17,704)	6,503
Effect of foreign exchange rate changes on cash and cash equivalents	(219)	(1,040)	(530)
Net increase (decrease) in cash and cash equivalents	71,188	(17,759)	6,576
Cash and cash equivalents, beginning of period	30,476	48,235	41,659
Cash and cash equivalents, end of period	101,664	30,476	48,235
Consolidating Eliminations
Cash Flows from Investing Activities:
Due from affiliates	137,227	279,391	309,310
Net cash used by investing activities	137,227	279,391	309,310
Cash Flows from Financing Activities:
Due to affiliates	(137,227)	(279,391)	(309,310)
Net cash provided (used) by financing activities	$ (137,227)	$ (279,391)	$ (309,310)