Fair Value - Presentation of Fair-Value Measurements for Each Major Category of Assets Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	$ 133,448	$ 117,212
Other investments	10,486	9,994
Cash, cash equivalents, and restricted cash	111,251	118,681
Total	255,185	245,887
Other investments, proportionate share of net assets	5,016	5,136
Total, proportionate share of net assets	5,016	5,136
Fixed Maturities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	117,351	101,589
Fixed Maturities | U.S. government and agencies
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	19,495	18,951
Fixed Maturities | Political subdivisions
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	4,172	4,165
Fixed Maturities | Revenue and assessment
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	5,450	5,683
Fixed Maturities | Corporate bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	43,670	45,540
Fixed Maturities | Collateralized mortgage obligations: Agency Backed
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	40,670	22,422
Fixed Maturities | Collateralized mortgage obligations: Non-agency backed - residential
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	2,713	2,933
Fixed Maturities | Collateralized mortgage obligations: Non-agency backed - commercial
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	1,181	1,895
Preferred stocks, available-for-sale
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	3,206	3,112
Mutual funds, available-for-sale
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	12,891	12,511
Fair Value Measurements Using Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	35,592	34,574
Cash, cash equivalents, and restricted cash	111,251	118,681
Total	146,843	153,255
Fair Value Measurements Using Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed Maturities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	19,495	18,951
Fair Value Measurements Using Quoted Prices in Active Markets for Identical Assets (Level 1) | Fixed Maturities | U.S. government and agencies
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	19,495	18,951
Fair Value Measurements Using Quoted Prices in Active Markets for Identical Assets (Level 1) | Preferred stocks, available-for-sale
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	3,206	3,112
Fair Value Measurements Using Quoted Prices in Active Markets for Identical Assets (Level 1) | Mutual funds, available-for-sale
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	12,891	12,511
Fair Value Measurements Using Significant Other Observable Inputs (Level 2)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	97,856	82,638
Total	97,856	82,638
Fair Value Measurements Using Significant Other Observable Inputs (Level 2) | Fixed Maturities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	97,856	82,638
Fair Value Measurements Using Significant Other Observable Inputs (Level 2) | Fixed Maturities | Political subdivisions
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	4,172	4,165
Fair Value Measurements Using Significant Other Observable Inputs (Level 2) | Fixed Maturities | Revenue and assessment
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	5,450	5,683
Fair Value Measurements Using Significant Other Observable Inputs (Level 2) | Fixed Maturities | Corporate bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	43,670	45,540
Fair Value Measurements Using Significant Other Observable Inputs (Level 2) | Fixed Maturities | Collateralized mortgage obligations: Agency Backed
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	40,670	22,422
Fair Value Measurements Using Significant Other Observable Inputs (Level 2) | Fixed Maturities | Collateralized mortgage obligations: Non-agency backed - residential
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	2,713	2,933
Fair Value Measurements Using Significant Other Observable Inputs (Level 2) | Fixed Maturities | Collateralized mortgage obligations: Non-agency backed - commercial
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	1,181	1,895
Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other investments	5,470	4,858
Total	$ 5,470	$ 4,858