Investments - Cost or Amortized Cost and Fair Value of Securities Available for Sale (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	$ 623,851	$ 650,575
Gross Unrealized Gains	2,635	1,201
Gross Unrealized Losses	(6,650)	(11,610)
Fair Value	619,836	640,166
Mortgage-Backed and Asset-Backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	211,044	216,679
Fair Value	209,768	214,776
Fixed Maturities [Member] \| U.S. Government Obligations and Agencies [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	78,049	74,937
Gross Unrealized Gains	35
Gross Unrealized Losses	(545)	(670)
Fair Value	77,539	74,267
Fixed Maturities [Member] \| Corporate Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	203,843	192,328
Gross Unrealized Gains	1,018	402
Gross Unrealized Losses	(658)	(1,300)
Fair Value	204,203	191,430
Fixed Maturities [Member] \| Mortgage-Backed and Asset-Backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	211,044	216,679
Gross Unrealized Gains	116	135
Gross Unrealized Losses	(1,392)	(2,038)
Fair Value	209,768	214,776
Fixed Maturities [Member] \| Municipal Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	105,110	94,794
Gross Unrealized Gains	638	130
Gross Unrealized Losses	(1,836)	(3,727)
Fair Value	103,912	91,197
Fixed Maturities [Member] \| Redeemable Preferred Stock [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	13,727	12,723
Gross Unrealized Gains	769	125
Gross Unrealized Losses	(9)	(157)
Fair Value	14,487	12,691
Equity Securities [Member] \| Mutual Funds [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost	12,078	53,900
Gross Unrealized Gains	59	407
Gross Unrealized Losses	(2,210)	(3,597)
Fair Value	$ 9,927	50,710
Equity Securities [Member] \| Common Stock [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost		214
Gross Unrealized Losses		(121)
Fair Value		93
Short-term Investments [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost or Amortized Cost		5,000
Gross Unrealized Gains		2
Fair Value		$ 5,002

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

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-Topic 320
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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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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