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DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2026 USD ($) collisionCenter franchise state dealership vehicleBrand shares	Mar. 31, 2026 USD ($) shares	Jun. 30, 2025 USD ($) shares	Mar. 31, 2025 USD ($) shares	Jun. 30, 2026 USD ($) collisionCenter franchise state dealership segment vehicleBrand shares	Jun. 30, 2025 USD ($) shares	Feb. 25, 2026 USD ($)
Business Organization [Line Items]
Number of franchises (in franchises) \| franchise	202				202
Number of dealership locations (in dealership locations) \| dealership	158				158
Number of vehicle brands (in vehicle brands) \| vehicleBrand	34				34
Number of collision repair centers (in collision repair centers) \| collisionCenter	37				37
Number of states (in states) \| state	14				14
Number of reportable segments \| segment					2
Repurchase and retirement of common stock (in shares) \| shares	668,116		0		1,346,359	0
Stock repurchase program, increase (decrease) in authorized amount							$ 424.0
Stock repurchase program, authorized amount							$ 500.0
Stock repurchase program, remaining authorized repurchase amount	$ 322.4				$ 322.4
Payments for repurchase of common stock	130.6				$ 277.6	$ 0.0
Retirement of common stock	0.0	$ 0.0
Repurchase of common stock associated with net share settlement of employee share-based awards	$ 0.1	$ 9.8	$ 0.2	$ 12.5
Treasury Stock
Business Organization [Line Items]
Repurchase and retirement of common stock (in shares) \| shares	668,116	678,243
Retirement of common stock	$ 130.6	$ 147.0
Repurchase of common stock associated with net share settlement of employee share-based awards (in shares) \| shares	817	37,420	646	42,780	38,237	43,426
Repurchase of common stock associated with net share settlement of employee share-based awards	$ 0.1	$ 9.8	$ 0.2	$ 12.5	$ 9.9	$ 12.7
Restricted Share Units
Business Organization [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares) \| shares	9,707		7,829		9,031	7,630
Performance share units
Business Organization [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares) \| shares	103		11		0	14
Luxury Brands
Business Organization [Line Items]
Weighted brand mix (percent)					33.00%
Mid-line Import Brands
Business Organization [Line Items]
Weighted brand mix (percent)					41.00%
Domestic Brands
Business Organization [Line Items]
Weighted brand mix (percent)					26.00%