Investments - Cost or Amortized Cost and Fair Value of Securities Available for Sale (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	$ 426,568	$ 355,052
Gross Unrealized Gains	514	3,541
Gross Unrealized Losses	(3,501)	(4,153)
Fair Value	423,581us-gaap_AvailableForSaleSecurities	354,440us-gaap_AvailableForSaleSecurities
U.S. Government Obligations and Agencies [Member] \| Fixed Maturities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	120,627	105,229
Gross Unrealized Gains	38	19
Gross Unrealized Losses	(627)	(1,033)
Fair Value	120,038	104,215
Corporate Bonds [Member] \| Fixed Maturities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	120,025	94,708
Gross Unrealized Gains	171	265
Gross Unrealized Losses	(364)	(770)
Fair Value	119,832	94,203
Mortgage-Backed and Asset-Backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	107,589	91,502
Fair Value	107,223	91,000
Mortgage-Backed and Asset-Backed Securities [Member] \| Fixed Maturities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	107,589	91,502
Gross Unrealized Gains	136	75
Gross Unrealized Losses	(502)	(577)
Fair Value	107,223	91,000
Redeemable Preferred Stock [Member] \| Fixed Maturities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	6,700
Gross Unrealized Gains	165
Gross Unrealized Losses	(9)
Fair Value	6,856
Common Stock [Member] \| Equity Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	331	8,500
Gross Unrealized Gains	4	916
Gross Unrealized Losses	(65)	(121)
Fair Value	270	9,295
Mutual Funds [Member] \| Equity Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	21,296	55,113
Gross Unrealized Gains		2,266
Gross Unrealized Losses	(1,924)	(1,652)
Fair Value	19,372	55,727
Short-term Investments [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	50,000
Gross Unrealized Losses	(10)
Fair Value	$ 49,990

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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-Publisher FASB

-Name Accounting Standards Codification

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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