v3.22.0.1
FAIR VALUE MEASUREMENTS - Fair value on a recurring basis (Details) - USD ($)
$ in Millions
Dec. 31, 2021
Dec. 31, 2020
Other long-term assets:    
The company's recorded investment $ 85.6 $ 80.9
Recurring basis    
Other long-term assets:    
Money market mutual funds 0.5 1.1
Investments measured at net asset value 12.4 10.6
The company's recorded investment   5.2
Total assets at fair value 12.9 16.9
Recurring basis | Quoted prices in active market (Level 1)    
Other long-term assets:    
Money market mutual funds 0.5 1.1
The company's recorded investment   5.2
Total assets at fair value $ 0.5 $ 6.3