Investments - Cost or Amortized Cost and Fair Value of Securities Available for Sale (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	$ 407,852	$ 426,568
Gross Unrealized Gains	1,699	514
Gross Unrealized Losses	(2,737)	(3,501)
Fair Value	406,814us-gaap_AvailableForSaleSecurities	423,581us-gaap_AvailableForSaleSecurities
Short-term Investments [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	37,500	50,000
Gross Unrealized Gains	6
Gross Unrealized Losses		(10)
Fair Value	37,506	49,990
U.S. Government Obligations and Agencies [Member] \| Fixed Maturities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	105,290	120,627
Gross Unrealized Gains	77	38
Gross Unrealized Losses	(175)	(627)
Fair Value	105,192	120,038
Corporate Bonds [Member] \| Fixed Maturities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	123,944	120,025
Gross Unrealized Gains	744	171
Gross Unrealized Losses	(114)	(364)
Fair Value	124,574	119,832
Mortgage-Backed and Asset-Backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	109,529	107,589
Fair Value	109,771	107,223
Mortgage-Backed and Asset-Backed Securities [Member] \| Fixed Maturities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	109,529	107,589
Gross Unrealized Gains	521	136
Gross Unrealized Losses	(279)	(502)
Fair Value	109,771	107,223
Redeemable Preferred Stock [Member] \| Fixed Maturities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	8,056	6,700
Gross Unrealized Gains	320	165
Gross Unrealized Losses	(1)	(9)
Fair Value	8,375	6,856
Common Stock [Member] \| Equity Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	2,215	331
Gross Unrealized Gains		4
Gross Unrealized Losses	(226)	(65)
Fair Value	1,989	270
Mutual Funds [Member] \| Equity Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	21,318	21,296
Gross Unrealized Gains	31
Gross Unrealized Losses	(1,942)	(1,924)
Fair Value	$ 19,407	$ 19,372

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 gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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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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