Liability for Unpaid Losses and Loss Adjustment Expenses - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Direct losses and loss adjustment expenses	$ 173,243	$ 115,742
Ceded Losses and Loss Adjustment Expenses	38,195	2,648
Incurred (recovered) related to prior years	4,341	$ (185)
Hurricane
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Direct losses and loss adjustment expenses	42,500
Ceded Losses and Loss Adjustment Expenses	38,200
Incurred (recovered) related to prior years	$ 4,300