Investment Securities - Schedule of Amortized Cost, Gross Unrealized Gains, Gross Unrealized Losses and Estimated Fair Values of Fixed-Maturity Securities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total fixed-maturity securities, Amortized Cost	$ 217,587	$ 272,895
Total fixed-maturity securities, Gross Unrealized Gains	1,730	4,869
Total fixed-maturity securities, Gross Unrealized Losses	(516)	(295)
Total fixed-maturity securities, Estimated Fair Value	218,801	277,469
Total fixed-maturity securities held in trust, Amortized Cost	144,909	197,236
Total fixed-maturity securities held in trust, Gross Unrealized Gains	1,498	4,701
Total fixed-maturity securities held in trust, Gross Unrealized Losses	(503)	(277)
Total fixed-maturity securities held in trust, Estimated Fair Value	145,904	201,660
Obligations of U.S. Government Sponsored Enterprises [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total fixed-maturity securities, Amortized Cost	15,868	97,103
Total fixed-maturity securities, Gross Unrealized Gains	127	1,416
Total fixed-maturity securities, Gross Unrealized Losses	(163)	(156)
Total fixed-maturity securities, Estimated Fair Value	15,832	98,363
Corporate Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total fixed-maturity securities, Amortized Cost	80,624	91,997
Total fixed-maturity securities, Gross Unrealized Gains	1,450	3,010
Total fixed-maturity securities, Gross Unrealized Losses	(182)	(34)
Total fixed-maturity securities, Estimated Fair Value	81,892	94,973
Commercial Paper [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total fixed-maturity securities, Amortized Cost	98,929	54,949
Total fixed-maturity securities, Gross Unrealized Gains	4
Total fixed-maturity securities, Gross Unrealized Losses	(1)
Total fixed-maturity securities, Estimated Fair Value	98,932	54,949
Foreign Corporate Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total fixed-maturity securities, Amortized Cost	22,166	18,305
Total fixed-maturity securities, Gross Unrealized Gains	149	379
Total fixed-maturity securities, Gross Unrealized Losses	(170)	(18)
Total fixed-maturity securities, Estimated Fair Value	22,145	18,666
Commercial Mortgage-Backed Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Total fixed-maturity securities, Amortized Cost		10,541
Total fixed-maturity securities, Gross Unrealized Gains		64
Total fixed-maturity securities, Gross Unrealized Losses		(87)
Total fixed-maturity securities, Estimated Fair Value		10,518
Trading [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Less total unrestricted fixed-maturity securities, Amortized Cost	7,326	14,246
Less total unrestricted fixed-maturity securities, Gross Unrealized Gains	232	168
Less total unrestricted fixed-maturity securities, Gross Unrealized Losses	(13)	(18)
Less total unrestricted fixed-maturity securities, Estimated Fair Value	7,545	14,396
Held to Maturity [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Less total unrestricted fixed-maturity securities, Amortized Cost	65,352	61,413
Less total unrestricted fixed-maturity securities, Gross Unrealized Gains
Less total unrestricted fixed-maturity securities, Gross Unrealized Losses
Less total unrestricted fixed-maturity securities, Estimated Fair Value	$ 65,352	$ 61,413