Acquisition - Additional Information (Detail) (USD $)	3 Months Ended								12 Months Ended			1 Months Ended	2 Months Ended	12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Nov. 30, 2012 Family Heritage [Member]	Dec. 31, 2012 Family Heritage [Member]	Dec. 31, 2013 Family Heritage [Member]	Dec. 31, 2012 Family Heritage [Member]
Business Acquisition [Line Items]
Business acquisition purchase price												$ 234,000,000
Debt assumed												20,000,000
Fair value of debt securities												20,000,000
Purchase price funded with cash												214,000,000
Acquisition expenses										2,944,000					2,900,000
Acquisition expenses net of tax									(522,000)	1,914,000	0				1,900,000
Adjustment for finalization of accounting for a business combination pretax	100,743,000	98,444,000	102,488,000	101,714,000	98,052,000	94,016,000	96,601,000	96,498,000	403,389,000	385,167,000	364,583,000			1,519,000
Adjustment for finalization of accounting for a business combination after tax														522,000
Increase in policy holder benefit reserve									578,217,000	497,306,000	431,362,000			8,500,000
Increase in deferred acquisition														10,000,000
Business Acquisition, Purchase Price Allocation, Goodwill, Expected Tax Deductible Amount														0
Revenue													33,000,000
Net Income													$ 3,100,000