Estimated Fair Value and Gross Unrealized Losses and Other-Than-Temporary Impairments related to Fixed Maturity and Equity Available-for-Sale Securities in Continuous Unrealized Loss Position (Detail) - USD ($) $ in Thousands		Jun. 30, 2016	Dec. 31, 2015
Gain (Loss) on Investments [Line Items]
Estimated Fair Value		$ 126,457	$ 283,146
Amortized Cost/Cost		133,767	303,986
Gross Unrealized Losses and OTTI	[1]	(7,310)	(20,840)
Less than or equal to six months
Gain (Loss) on Investments [Line Items]
Estimated Fair Value		49,290	229,334
Amortized Cost/Cost		50,241	239,090
Gross Unrealized Losses and OTTI	[1]	(951)	(9,756)
Less than or equal to six months | Fixed maturity AFS securities | Corporate securities
Gain (Loss) on Investments [Line Items]
Estimated Fair Value		8,146	130,718
Amortized Cost/Cost		8,604	139,846
Gross Unrealized Losses and OTTI	[1]	(458)	(9,128)
Less than or equal to six months | Fixed maturity AFS securities | Asset-backed securities
Gain (Loss) on Investments [Line Items]
Estimated Fair Value		24,005	59,051
Amortized Cost/Cost		24,164	59,312
Gross Unrealized Losses and OTTI	[1]	(159)	(261)
Less than or equal to six months | Fixed maturity AFS securities | Commercial mortgage-backed securities
Gain (Loss) on Investments [Line Items]
Estimated Fair Value		2,674	17,185
Amortized Cost/Cost		2,680	17,450
Gross Unrealized Losses and OTTI	[1]	(6)	(265)
Less than or equal to six months | Fixed maturity AFS securities | Residential mortgage-backed securities
Gain (Loss) on Investments [Line Items]
Estimated Fair Value		14,465	3,896
Amortized Cost/Cost		14,793	3,966
Gross Unrealized Losses and OTTI	[1]	(328)	(70)
Less than or equal to six months | Fixed maturity AFS securities | Government and government agencies - United States
Gain (Loss) on Investments [Line Items]
Estimated Fair Value			18,484
Amortized Cost/Cost			18,516
Gross Unrealized Losses and OTTI	[1]		(32)
Greater than six months but less than or equal to one year
Gain (Loss) on Investments [Line Items]
Estimated Fair Value		34,434	30,335
Amortized Cost/Cost		37,113	33,118
Gross Unrealized Losses and OTTI	[1]	(2,679)	(2,783)
Greater than six months but less than or equal to one year | Fixed maturity AFS securities | Corporate securities
Gain (Loss) on Investments [Line Items]
Estimated Fair Value		24,978	27,872
Amortized Cost/Cost		27,383	30,597
Gross Unrealized Losses and OTTI	[1]	(2,405)	(2,725)
Greater than six months but less than or equal to one year | Fixed maturity AFS securities | Asset-backed securities
Gain (Loss) on Investments [Line Items]
Estimated Fair Value		6,734	455
Amortized Cost/Cost		6,887	463
Gross Unrealized Losses and OTTI	[1]	(153)	(8)
Greater than six months but less than or equal to one year | Fixed maturity AFS securities | Commercial mortgage-backed securities
Gain (Loss) on Investments [Line Items]
Estimated Fair Value		481	988
Amortized Cost/Cost		486	1,028
Gross Unrealized Losses and OTTI	[1]	(5)	(40)
Greater than six months but less than or equal to one year | Fixed maturity AFS securities | Residential mortgage-backed securities
Gain (Loss) on Investments [Line Items]
Estimated Fair Value		2,241	1,020
Amortized Cost/Cost		2,357	1,030
Gross Unrealized Losses and OTTI	[1]	(116)	(10)
Greater than one year
Gain (Loss) on Investments [Line Items]
Estimated Fair Value		42,733	23,477
Amortized Cost/Cost		46,413	31,778
Gross Unrealized Losses and OTTI	[1]	(3,680)	(8,301)
Greater than one year | Fixed maturity AFS securities | Corporate securities
Gain (Loss) on Investments [Line Items]
Estimated Fair Value		26,157	8,628
Amortized Cost/Cost		28,973	15,531
Gross Unrealized Losses and OTTI	[1]	(2,816)	(6,903)
Greater than one year | Fixed maturity AFS securities | Asset-backed securities
Gain (Loss) on Investments [Line Items]
Estimated Fair Value		5,269	4,788
Amortized Cost/Cost		5,368	4,999
Gross Unrealized Losses and OTTI	[1]	(99)	(211)
Greater than one year | Fixed maturity AFS securities | Residential mortgage-backed securities
Gain (Loss) on Investments [Line Items]
Estimated Fair Value		817	39
Amortized Cost/Cost		865	40
Gross Unrealized Losses and OTTI	[1]	(48)	(1)
Greater than one year | Fixed maturity AFS securities | Municipals
Gain (Loss) on Investments [Line Items]
Estimated Fair Value		807	808
Amortized Cost/Cost		911	912
Gross Unrealized Losses and OTTI	[1]	(104)	(104)
Greater than one year | Equity AFS securities | Banking securities
Gain (Loss) on Investments [Line Items]
Estimated Fair Value		9,683	9,214
Amortized Cost/Cost		10,296	10,296
Gross Unrealized Losses and OTTI	[1]	$ (613)	$ (1,082)

[1] Subsequent unrealized gains (losses) on OTTI securities are included in OCI-OTTI.