Fair Value - Presentation of Fair-Value Measurements for Each Major Category of Assets Measured on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	$ 125,085	$ 130,248
Other investments	10,530	7,513
Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	125,085	130,248
Other investments	10,530	7,513
Cash and cash equivalents	102,429	72,033
Total	238,044	209,794
Preferred Stock | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	1,767	1,578
Equity Funds | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Mutual funds, available-for-sale	10,296	10,737
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	20,353	24,800
Cash and cash equivalents	102,429	72,033
Total	122,782	96,833
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Preferred Stock | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	1,767	1,578
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity Funds | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Mutual funds, available-for-sale	10,296	10,737
Significant Other Observable Inputs (Level 2) [Member] | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	104,732	105,448
Total	104,732	105,448
Significant Unobservable Inputs (Level 3) [Member] | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Other investments	10,530	7,513
Total	10,530	7,513
Fixed Maturities | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	113,022	117,933
Fixed Maturities | US Government Agencies Debt Securities | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	8,290	12,485
Fixed Maturities | State Securities | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	725	736
Fixed Maturities | Political Subdivisions Securities | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	506	1,652
Fixed Maturities | Revenue And Assessment Securities | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	16,360	13,618
Fixed Maturities | Corporate Bond Securities | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	75,119	73,325
Fixed Maturities | Collateralized Agency Backed Obligations | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	4,807	7,514
Fixed Maturities | Collateralized Non Agency Backed Residential Obligations | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	4,137	4,660
Fixed Maturities | Collateralized Non Agency Backed Commercial Obligations | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	3,078	3,943
Fixed Maturities | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	8,290	12,485
Fixed Maturities | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | US Government Agencies Debt Securities | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	8,290	12,485
Fixed Maturities | Significant Other Observable Inputs (Level 2) [Member] | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	104,732	105,448
Fixed Maturities | Significant Other Observable Inputs (Level 2) [Member] | State Securities | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	725	736
Fixed Maturities | Significant Other Observable Inputs (Level 2) [Member] | Political Subdivisions Securities | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	506	1,652
Fixed Maturities | Significant Other Observable Inputs (Level 2) [Member] | Revenue And Assessment Securities | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	16,360	13,618
Fixed Maturities | Significant Other Observable Inputs (Level 2) [Member] | Corporate Bond Securities | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	75,119	73,325
Fixed Maturities | Significant Other Observable Inputs (Level 2) [Member] | Collateralized Agency Backed Obligations | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	4,807	7,514
Fixed Maturities | Significant Other Observable Inputs (Level 2) [Member] | Collateralized Non Agency Backed Residential Obligations | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	4,137	4,660
Fixed Maturities | Significant Other Observable Inputs (Level 2) [Member] | Collateralized Non Agency Backed Commercial Obligations | Fair Value Measurements Using [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Investments, available-for-sale	$ 3,078	$ 3,943