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MARKETABLE INVESTMENT SECURITIES - Schedule of Fair Value for Available-for-Sale Securities by Major Security Type and Class of Security (Details) - USD ($)
$ in Millions
Mar. 31, 2023
Dec. 31, 2022
Mar. 31, 2022
Cash and cash equivalents:      
Amortized cost $ 53.6 $ 56.9 $ 164.2
Estimated fair value 53.6 56.9  
Total      
Amortized cost 110.6 172.4  
Gross unrealized holding gains 0.0 0.0  
Gross unrealized holding losses (1.5) (2.7)  
Estimated fair value 109.1 169.7  
Corporate bonds and notes      
Available-for-sale:      
Amortized cost 29.3 66.7  
Gross unrealized holding gains 0.0 0.0  
Gross unrealized holding losses (0.9) (1.6)  
Estimated fair value 28.4 65.1  
Municipal bonds      
Available-for-sale:      
Amortized cost 8.7 16.3  
Gross unrealized holding gains 0.0 0.0  
Gross unrealized holding losses (0.1) (0.3)  
Estimated fair value 8.6 16.0  
Federal agency issues      
Available-for-sale:      
Amortized cost 14.5 20.7  
Gross unrealized holding gains 0.0 0.0  
Gross unrealized holding losses (0.4) (0.7)  
Estimated fair value 14.1 20.0  
U.S. government securities      
Available-for-sale:      
Amortized cost 4.5 11.8  
Gross unrealized holding gains 0.0 0.0  
Gross unrealized holding losses (0.1) (0.1)  
Estimated fair value 4.4 11.7  
Cash      
Cash and cash equivalents:      
Amortized cost 51.9 53.6  
Estimated fair value 51.9 53.6  
Cash equivalents      
Cash and cash equivalents:      
Amortized cost 1.7 3.3  
Estimated fair value $ 1.7 $ 3.3