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Earnings Per Share - Narrative (Details)
6 Months Ended
Apr. 04, 2018
USD ($)
shares
Mar. 27, 2018
USD ($)
Jun. 30, 2019
shares
Debt Instrument [Line Items]      
Conversion ratio   0.0323428  
Aggregate number of shares (shares) 1,858,500    
Unsecured obligations | 2.50% Convertible notes due 2023      
Debt Instrument [Line Items]      
Aggregate principal amount | $ $ 171,500,000 $ 150,000,000.0  
Conversion multiple | $ $ 1,000    
Shares issued (shares)     0
Number of shares issuable upon conversion (shares)     5,500,000