Separate Financial Information of Guarantor Subsidiaries - Condensed Consolidating Statement of Earnings and Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Condensed Income Statements Captions [Line Items]
Net sales	$ 957,812	$ 705,287	$ 871,023	$ 980,208	$ 965,937	$ 975,169	$ 945,852	$ 989,453	$ 3,514,330	$ 3,876,411	$ 3,932,565
Cost of goods sold									1,798,736	1,965,869	1,988,152
Gross profit	489,143	321,846	429,757	474,848	479,291	482,222	468,324	480,705	1,715,594	1,910,542	1,944,413
Selling, general and administrative expenses									1,442,809	1,452,751	1,484,209
Restructuring									14,025	(682)	33,615
Operating earnings									258,760	458,473	426,589
Interest expense (income)									98,793	96,309	98,162
Earnings before provision for income taxes									159,967	362,164	328,427
Provision (benefit) for income taxes									46,722	90,541	70,380
Net earnings	$ 70,188	$ (23,526)	$ 13,368	$ 53,215	$ 69,007	$ 71,164	$ 65,725	$ 65,727	113,245	271,623	258,047
Other comprehensive income (loss), net of tax									12,584	(27,296)	(8,155)
Total comprehensive income									125,829	244,327	249,892
Parent
Condensed Income Statements Captions [Line Items]
Selling, general and administrative expenses									11,501	11,331	10,957
Operating earnings									(11,501)	(11,331)	(10,957)
Earnings before provision for income taxes									(11,501)	(11,331)	(10,957)
Provision (benefit) for income taxes									(2,901)	(2,742)	(2,734)
Equity (loss) in earnings of subsidiaries, net of tax									121,845	280,212	266,270
Net earnings									113,245	271,623	258,047
Total comprehensive income									113,245	271,623	258,047
Sally Holdings and Sally Capital
Condensed Income Statements Captions [Line Items]
Selling, general and administrative expenses									753	607	1,538
Operating earnings									(753)	(607)	(1,538)
Interest expense (income)									98,998	96,464	98,332
Earnings before provision for income taxes									(99,751)	(97,071)	(99,870)
Provision (benefit) for income taxes									(25,476)	(24,888)	(28,787)
Equity (loss) in earnings of subsidiaries, net of tax									196,120	352,395	337,353
Net earnings									121,845	280,212	266,270
Other comprehensive income (loss), net of tax									198	(4,566)	2,449
Total comprehensive income									122,043	275,646	268,719
Guarantor Subsidiaries
Condensed Income Statements Captions [Line Items]
Net sales									2,883,265	3,131,360	3,152,120
Related party sales									1,761	2,201	2,294
Cost of goods sold									1,447,705	1,568,663	1,581,385
Gross profit									1,437,321	1,564,898	1,573,029
Selling, general and administrative expenses									1,152,489	1,135,926	1,136,312
Restructuring									14,025	(682)	33,615
Operating earnings									270,807	429,654	403,102
Interest expense (income)									(131)	5	(3)
Earnings before provision for income taxes									270,938	429,649	403,105
Provision (benefit) for income taxes									70,840	109,230	73,747
Equity (loss) in earnings of subsidiaries, net of tax									(3,978)	31,976	7,995
Net earnings									196,120	352,395	337,353
Total comprehensive income									196,120	352,395	337,353
Non-Guarantor Subsidiaries
Condensed Income Statements Captions [Line Items]
Net sales									631,065	745,051	780,445
Cost of goods sold									352,792	399,407	409,061
Gross profit									278,273	345,644	371,384
Selling, general and administrative expenses									278,066	304,887	335,402
Operating earnings									207	40,757	35,982
Interest expense (income)									(74)	(160)	(167)
Earnings before provision for income taxes									281	40,917	36,149
Provision (benefit) for income taxes									4,259	8,941	28,154
Net earnings									(3,978)	31,976	7,995
Other comprehensive income (loss), net of tax									12,386	(22,730)	(10,604)
Total comprehensive income									8,408	9,246	(2,609)
Consolidating Eliminations
Condensed Income Statements Captions [Line Items]
Related party sales									(1,761)	(2,201)	(2,294)
Cost of goods sold									(1,761)	(2,201)	(2,294)
Equity (loss) in earnings of subsidiaries, net of tax									(313,987)	(664,583)	(611,618)
Net earnings									(313,987)	(664,583)	(611,618)
Total comprehensive income									$ (313,987)	$ (664,583)	$ (611,618)