Unpaid Claims - Summary of Cumulative Incurred Claims (Details)
$ in Thousands
Dec. 31, 2020
USD ($)
Number
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Disclosure Details Of Liability For Claims Incurred And Reported And Not Reported [Line Items]      
Reported Claims $ 1,552,841    
Total IBNR $ 103,976    
Number of reported claims | Number 4,359,205    
2018 and prior [Member]      
Disclosure Details Of Liability For Claims Incurred And Reported And Not Reported [Line Items]      
Total IBNR $ 2    
Number of reported claims | Number 1,737,684    
2019 [Member]      
Disclosure Details Of Liability For Claims Incurred And Reported And Not Reported [Line Items]      
Total IBNR $ 1,130    
Number of reported claims | Number 1,188,472    
2020 [Member]      
Disclosure Details Of Liability For Claims Incurred And Reported And Not Reported [Line Items]      
Total IBNR $ 102,844    
Number of reported claims | Number 1,433,049    
Cumulative Liability Year One [Member]      
Disclosure Details Of Liability For Claims Incurred And Reported And Not Reported [Line Items]      
Reported Claims     $ 552,456
Cumulative Liability Year One [Member] | 2018 and prior [Member]      
Disclosure Details Of Liability For Claims Incurred And Reported And Not Reported [Line Items]      
Reported Claims     $ 552,456
Cumulative Liability Year Two [Member]      
Disclosure Details Of Liability For Claims Incurred And Reported And Not Reported [Line Items]      
Reported Claims   $ 962,373  
Cumulative Liability Year Two [Member] | 2018 and prior [Member]      
Disclosure Details Of Liability For Claims Incurred And Reported And Not Reported [Line Items]      
Reported Claims   549,678  
Cumulative Liability Year Two [Member] | 2019 [Member]      
Disclosure Details Of Liability For Claims Incurred And Reported And Not Reported [Line Items]      
Reported Claims   $ 412,695  
Cumulative Liability Year Three [Member]      
Disclosure Details Of Liability For Claims Incurred And Reported And Not Reported [Line Items]      
Reported Claims $ 1,552,841    
Cumulative Liability Year Three [Member] | 2018 and prior [Member]      
Disclosure Details Of Liability For Claims Incurred And Reported And Not Reported [Line Items]      
Reported Claims 549,649    
Cumulative Liability Year Three [Member] | 2019 [Member]      
Disclosure Details Of Liability For Claims Incurred And Reported And Not Reported [Line Items]      
Reported Claims 399,009    
Cumulative Liability Year Three [Member] | 2020 [Member]      
Disclosure Details Of Liability For Claims Incurred And Reported And Not Reported [Line Items]      
Reported Claims $ 604,183