Unpaid Claims - Summary of Reconcilation of Claims Incurred and Paid And Unpaid Claims (Details) - USD ($)
$ in Thousands
Mar. 31, 2021
Dec. 31, 2020
Mar. 31, 2020
Dec. 31, 2019
Roll Forward In Liability For Unpaid Claims And Claims Adjustment Expense [Abstract]        
Cumulative incurred claims, net   $ 1,552,841    
Less: cumulative paid claims, net   1,448,865    
Net unpaid claims, including claims adjustment expenses $ 117,582 $ 103,976 $ 90,353 $ 77,886