Accounts Payable and Other Liabilities - Schedule of Accounts Payable and Other Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Other Liabilities Disclosure [Abstract]
Deferred ceding commission	$ 35,185	$ 44,996
Outstanding claim checks		15,360
Accounts payable and other payables	7,096	8,379
Lease obligations	8,635
Accrued interest and issuance costs	1,476	1,285
Accrued dividends	1,772	1,589
Premium tax		2,241
Other liabilities	37	460
Commission payables	12,228	11,654
Total other liabilities	$ 66,428	$ 85,964