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Fair Value Narrative (Details) - USD ($)
$ in Millions
12 Months Ended
Feb. 26, 2021
Feb. 28, 2020
Feb. 22, 2019
May 29, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]        
Unrealized gain (loss) on investments $ 0.5 $ (0.1) $ 0.4  
Managed Investment Portfolio and Other Investments [Member]        
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]        
Available-for-sale Securities, Amortized Cost Basis   0.0   $ 0.0
Unrealized gain (loss) on investments 0.0      
Auction Rate Securities [Member]        
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]        
Unrealized gain (loss) on investments 0.3      
Available-for-sale Securities, Par Value 3.2      
Other than Temporary Impairment Losses, Investments 0.9      
Available-for-Sale Securities, Maturities [Abstract]        
Estimated Reduction in Fair Value due to a One Hundred Basis Point Increase in Discount Rate 0.4      
Fair Value, Recurring [Member] | Auction Rate Securities [Member]        
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]        
Available-for-sale Securities, Fair Value Disclosure 2.6 2.1    
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Auction Rate Securities [Member]        
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]        
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales   0.5    
Available-for-sale Securities, Fair Value Disclosure $ 2.6 $ 2.1 $ 3.9