Segment Reporting - Schedule of Disaggregation of Net Sales by Segment (Details) - Sales Revenue, Net - Product Concentration Risk	3 Months Ended		6 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2025	Mar. 31, 2024
SBS
Disaggregation Of Revenue [Line Items]
Percentage of net sales	100.00%	100.00%	100.00%	100.00%
SBS | Hair color
Disaggregation Of Revenue [Line Items]
Percentage of net sales	42.30%	39.60%	41.30%	39.20%
SBS | Hair care
Disaggregation Of Revenue [Line Items]
Percentage of net sales	23.60%	25.20%	23.70%	24.60%
SBS | Styling tools and supplies
Disaggregation Of Revenue [Line Items]
Percentage of net sales	16.20%	17.00%	16.80%	17.60%
SBS | Nail
Disaggregation Of Revenue [Line Items]
Percentage of net sales	10.00%	9.90%	10.00%	10.00%
SBS | Skin and cosmetics
Disaggregation Of Revenue [Line Items]
Percentage of net sales	7.40%	7.90%	7.60%	8.00%
SBS | Other Beauty items
Disaggregation Of Revenue [Line Items]
Percentage of net sales	0.50%	0.40%	0.60%	0.60%
SBS | Sales channel, directly to consumer | Company-operated stores
Disaggregation Of Revenue [Line Items]
Percentage of net sales	91.80%	93.40%	92.00%	93.30%
SBS | Sales channel, through intermediary | E-commerce
Disaggregation Of Revenue [Line Items]
Percentage of net sales	8.20%	6.60%	8.00%	6.70%
BSG
Disaggregation Of Revenue [Line Items]
Percentage of net sales	100.00%	100.00%	100.00%	100.00%
BSG | Hair color
Disaggregation Of Revenue [Line Items]
Percentage of net sales	42.80%	41.50%	41.40%	40.40%
BSG | Hair care
Disaggregation Of Revenue [Line Items]
Percentage of net sales	40.90%	41.80%	41.90%	42.40%
BSG | Styling tools and supplies
Disaggregation Of Revenue [Line Items]
Percentage of net sales	10.50%	10.60%	10.60%	10.70%
BSG | Nail
Disaggregation Of Revenue [Line Items]
Percentage of net sales	2.20%	2.30%	2.30%	2.40%
BSG | Skin and cosmetics
Disaggregation Of Revenue [Line Items]
Percentage of net sales	3.40%	3.50%	3.60%	3.90%
BSG | Other Beauty items
Disaggregation Of Revenue [Line Items]
Percentage of net sales	0.20%	0.30%	0.20%	0.20%
BSG | Sales channel, directly to consumer | Company-operated stores
Disaggregation Of Revenue [Line Items]
Percentage of net sales	69.30%	67.80%	69.40%	68.20%
BSG | Sales channel, through intermediary | Distributor sales consultants
Disaggregation Of Revenue [Line Items]
Percentage of net sales	9.30%	10.50%	9.50%	10.60%
BSG | Sales channel, through intermediary | E-commerce
Disaggregation Of Revenue [Line Items]
Percentage of net sales	13.90%	14.10%	14.00%	13.90%
BSG | Sales channel, through intermediary | Franchise stores
Disaggregation Of Revenue [Line Items]
Percentage of net sales	7.50%	7.60%	7.10%	7.30%