STOCK‐BASED COMPENSATION - Restricted Stock Units Narrative (Details) $ / shares in Units, $ in Millions		1 Months Ended					12 Months Ended
	Sep. 18, 2025 USD ($)	Aug. 31, 2025 shares	Jan. 31, 2025 shares	Oct. 31, 2024 USD ($) shares	May 31, 2024 USD ($) shares	Feb. 29, 2024 USD ($) day $ / shares shares	Dec. 31, 2025 USD ($) $ / shares shares	Dec. 31, 2024 USD ($) $ / shares	Dec. 31, 2023 USD ($) day $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Consecutive trading days for volume-weighted-average price | day									30
Stock-based compensation expense	$ 1,400.7						$ 1,447.7	$ 7.7	$ 34.9
Options granted, estimated grant date fair value										$ 19.7
Awards cancelled or forfeited (in shares) | shares		462,500
GMS Performance RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock-based compensation							$ 37.1
Unrecognized share-based compensation cost, period of recognition							2 years 10 months 24 days
Stock Price Target Performance RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares) | shares						462,500			7,116,935	500,000
Awards granted, grant date fair value										$ 4.8
Plan modification, number of shares (in shares) | shares				462,500
Consecutive trading days for volume-weighted-average price | day						60			30
Plan modification, aggregate award value				$ 15.4
Performance condition, shares to be issued upon occurrence of a liquidity event (in shares) | shares									3,250,000
Options granted, estimated grant date fair value						$ 15.3			$ 201.6
Stock Price Target Performance RSUs | 2018 Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense							$ 18.3	0.0	0.0
Unrecognized stock-based compensation							$ 0.1
Unrecognized share-based compensation cost, period of recognition							2 months 12 days
Stock Price Target Performance RSUs | 2023 Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense							$ 194.8	0.0	$ 0.0
Unrecognized stock-based compensation							$ 6.8
Unrecognized share-based compensation cost, period of recognition							7 months 6 days
Stock Price Target Performance RSUs | February 2024 Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense							$ (1.5)	1.5
Stock Price Target Performance RSUs | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting provisions, share price achievement (in dollars per share) | $ / shares						$ 40.04			$ 37.18	$ 19.50
Stock Price Target Performance RSUs | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting provisions, share price achievement (in dollars per share) | $ / shares						$ 127.40			$ 151.80	$ 65.00
Stock Price Target Performance RSUs, modified
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Plan modification, number of shares (in shares) | shares					500,000				500,000
Consecutive trading days for volume-weighted-average price | day									30
Plan modification, aggregate award value					$ 18.4				$ 17.9
Stock Price Target Performance RSUs, modified | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting provisions, share price achievement (in dollars per share) | $ / shares									$ 19.50
Stock Price Target Performance RSUs, modified | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting provisions, share price achievement (in dollars per share) | $ / shares									$ 65.00
GMS Performance RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares) | shares									4,023,387
Awards granted, grant date fair value									$ 143.6
Achievement of GMS targets, trailing period									12 months
GMS Performance RSUs | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance conditions, GMS target									$ 5,500.0
GMS Performance RSUs | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance conditions, GMS target									$ 16,500.0
GMS Performance RSUs with market conditions
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares) | shares									3,093,548
Awards granted, grant date fair value									$ 102.3
Consecutive trading days for volume-weighted-average price | day									30
Stock-based compensation expense							$ 208.8	0.0	$ 0.0
GMS Performance RSUs with market conditions | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting provisions, share price achievement (in dollars per share) | $ / shares									$ 37.20
GMS Performance RSUs with market conditions | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting provisions, share price achievement (in dollars per share) | $ / shares									$ 50.60
Other RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in dollars per share) | $ / shares							$ 38.76
Granted (in shares) | shares							2,838,393
Stock-based compensation expense							$ 790.6	$ 0.0	$ 0.0
Unrecognized stock-based compensation							$ 121.7
Unrecognized share-based compensation cost, period of recognition							1 year 10 months 24 days
Awards cancelled or forfeited (in shares) | shares							1,706,163
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in dollars per share) | $ / shares							$ 38.76	$ 38.07	$ 33.21
Fair value of RSUs vested							$ 428.7	$ 0.5	$ 0.8
Granted (in shares) | shares							2,838,393
Stock-based compensation expense							$ 0.0
Awards cancelled or forfeited (in shares) | shares			38,860				2,168,663