Estimated Fair Value of Assets Not Carried at Fair Value on Balance Sheets (Detail) (Estimate of Fair Value, Fair Value Disclosure, USD $) In Thousands, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Assets	$ 827,242		$ 854,435
Mortgages
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Assets	60,430	[1]	61,833	[1]
Policy loans
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Assets	766,812	[2]	792,602	[2]
Level 2
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Assets	766,812		792,602
Level 2 | Policy loans
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Assets	766,812	[2]	792,602	[2]
Level 3
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Assets	60,430		61,833
Level 3 | Mortgages
Fair Value, Estimate Not Practicable, Financial Statement Captions [Line Items]
Assets	$ 60,430	[1]	$ 61,833	[1]

[1] The fair value of mortgage loans on real estate is estimated by discounting the future cash flows using the current rates at which similar loans would be made to borrowers with similar credit ratings and/or similar remaining maturities.

[2] Policy loans are stated at unpaid principal balance. Fair value is estimated as equal to the book value of the loan.