XML 62 R59.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
Reporting and Accounting Policies - Additional Information (Details) - USD ($)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Apr. 01, 2018
Dec. 31, 2017
Property, Plant and Equipment [Line Items]        
Derivative Assets (Liabilities), at Fair Value, Net $ 0 $ 0    
Held for sale property $ 32,900,000 39,300,000    
Accelerated vesting percentage 50.00%      
Open reverse repurchase commitments $ 0 $ 0    
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability 63,100,000      
Unrecorded Unconditional Purchase Obligation $ 857,000,000.0      
ARX Holding Corp.        
Property, Plant and Equipment [Line Items]        
Equity interest percentage 87.10% 86.80%   69.00%
Cash and Cash Equivalents [Member] | ARX Holding Corp.        
Property, Plant and Equipment [Line Items]        
Open reverse repurchase commitments $ 46,300,000 $ 117,300,000   $ 247,200,000
Lower Limit | ARX Holding Corp.        
Property, Plant and Equipment [Line Items]        
Equity interest percentage     80.00%  
Common Stock [Member]        
Property, Plant and Equipment [Line Items]        
Dividends payable 1,375,400,000      
unrecorded unconditional purchase obligations reinsurance [Member] | Lower Limit        
Property, Plant and Equipment [Line Items]        
Other Commitment $ 96,100,000