Liability for Unpaid Losses and Loss Adjustment Expense - Reconciliation (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Reinsurance Recoverables on Unpaid Losses	$ 482,315	$ 477,870	$ 305,673
Short-duration Insurance Contracts, Liability for Unpaid Claims and Claims Adjustment Expense, Accumulated Unallocated Claim Adjustment Expense	13,486	11,449
Unpaid losses and loss adjustment expenses	760,357	661,203	$ 482,232	$ 140,855
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	264,556	171,884
Property and Casualty, Personal Insurance Product Line
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability
Reinsurance Recoverables on Unpaid Losses	482,315	477,870
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net	$ 264,556	$ 171,884