Losses and Loss Adjustment Reserve - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016 USD ($) Reinsurer	Dec. 31, 2015 USD ($)
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Ceded rate of premiums under insurance program	100.00%
Premiums written net	$ 591,124,000	$ 599,807,000
Reinsurance Recoverables on Unpaid Losses, Gross	78,100,000	32,000,000
Prepaid reinsurance premiums	308,661,000	309,643,000
Increase (Decrease) in Loss and Loss Adjustment Expense Reserve	0
Reserve For Losses And Loss Adjustment Expenses For Reinsurance Liability	$ 78,100,000	32,000,000
Number of reinsurers | Reinsurer	2
Homeowners
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Reinsurance Recoverables on Unpaid Losses, Gross	$ 5,262
Private Passenger Auto Liability
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Reinsurance Recoverables on Unpaid Losses, Gross	0
Other Liability
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Reinsurance Recoverables on Unpaid Losses, Gross	$ 95
Wright National Flood Insurance Company [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Ceded rate of premiums under insurance program	100.00%
Percentage of reinsurance recoverables allowance	30.90%
Premiums written net	$ 589,492,000	598,402,000
Wright National Flood Insurance Company [Member] | Quota Share Agreement
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Effective cedes rate under quota share agreement	100.00%
Commission rate, percent of ceded written premiums	30.50%
Wright National Flood Insurance Company [Member] | Quota Share Agreement | Reinsurer Concentration Risk [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Ceded amount	$ 1,600,000	$ 1,400,000