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Debt - Additional Information (Detail) - USD ($)
$ in Millions
9 Months Ended
May 20, 2019
Feb. 12, 2018
Sep. 30, 2019
Dec. 31, 2018
Debt Instrument [Line Items]        
Mortgage loan outstanding balance     $ 360.5 $ 364.8
Cash collateral for mortgage loan     $ 2.9  
7.25% Senior Unsecured Notes due 2021 [Member]        
Debt Instrument [Line Items]        
Interest rate on loan 7.25% 7.25%    
Borrowed amount   $ 25.0    
Debt instrument maturity date     Feb. 15, 2021  
Debt instrument redeemed date May 20, 2019   May 20, 2019  
Notes face value   101.00%