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Fair Value Measurements (Details) - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 1991
Apr. 18, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Abstract]        
Redemption amount of senior redeemable preferred stock       $ 2.1
Preferred stock dividend rate per annum   12.00%    
Public Preferred Stock [Member]        
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Abstract]        
Preferred stock dividend rate per annum 12.00%   6.00%  
Public preferred stock par value (in dollar per share) $ 0.01      
Carrying value of public preferred stock $ 135.4 $ 131.6    
Estimate of Fair Value, Fair Value Disclosure [Member] | Public Preferred Stock [Member]        
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Abstract]        
Public preferred stock $ 41.4 $ 42.2