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Fair Value Narrative (Details) - USD ($)
$ in Millions
12 Months Ended
Feb. 22, 2019
Feb. 23, 2018
Feb. 24, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Unrealized gain (loss) on investments $ 0.4 $ 0.0 $ (1.4)
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 0.1    
Available-for-sale Securities, Par Value 6.5    
Other than Temporary Impairment Losses, Investments 2.5    
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, Measurements, Recurring [Member] | Auction Rate Securities [Member]      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Available-for-sale Securities, Fair Value Disclosure 3.9 3.5  
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Auction Rate Securities [Member]      
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]      
Available-for-sale Securities, Fair Value Disclosure $ 3.9 $ 3.5 $ 3.5