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Debt - Senior Notes and Lenexa Mortgage (Details) - USD ($)
Mar. 08, 2017
Sep. 30, 2020
Dec. 31, 2019
Nov. 08, 2017
Jul. 23, 2014
Lenexa Mortgage          
Debt Instrument [Line Items]          
Interest rate 4.10%        
Aggregate principal amount $ 1,900,000        
Periodic principal payments $ 1,600,000        
Outstanding debt   $ 1,700,000      
Senior Notes          
Debt Instrument [Line Items]          
Interest rate   4.75%   4.75% 5.875%
Aggregate principal amount       $ 400,000,000.0  
Percentage of issued price equal to face value       100.00%  
Debt issuance costs, net   $ 3,900,000      
Outstanding debt   $ 400,000,000 $ 400,000,000