Analysis Of Profitability By Segment (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Segment Reporting Information [Line Items]
Pretax operating income									$ 753,592		$ 732,035		$ 722,383
Applicable taxes									(246,945)		(238,335)		(242,558)
After-tax total, before discontinued operations									506,647		493,700		479,825
Discontinued operations (after tax)									0		0		27,932
Net operating income									506,647		493,700		507,757
Realized gains (losses)-investments (after tax)									24,591	[1]	16,838	[1]	24,270	[1]
Realized gains (losses)-discontinued operations (after tax)									0	[1]	0	[1]	1,852	[1]
Loss on disposal of discontinued operations (after tax)									0		(455)		(35,013)
Acquisition expense-Family Heritage (after tax)									(1,914)		0		0
Cost of legal settlements (after tax)									0		(7,800)		0
State administrative settlement (after tax)									0		(4,486)		0
Loss on sale of equipment (after tax)									0		(636)		0
Net income	150,987	130,672	128,988	118,677	122,839	131,400	142,781	100,141	529,324		497,161		498,866
Pretax operating income, Change									21,557		9,652
Applicable taxes, Change									(8,610)		4,223
After-tax total net operating income, before discontinued operations, Change									12,947		13,875
Discontinued operations (after tax), Change									0		(27,932)
Net operating income, change									12,947		(14,057)
Realized gains (losses)-investments (after tax), Change									7,753	[1]	(7,432)	[1]
Realized gains (losses)-discontinued operations (after tax), Change									0	[1]	(1,852)	[1]
Loss on disposal of discontinued operations (after tax), Change									455		34,558
Acquisition expense-Family Heritage (after tax), Change									(1,914)		0
Cost of legal settlements (after tax), Change									7,800		(7,800)
State administrative settlement (after tax), Change									4,486		(4,486)
Loss on sale of equipment (after tax), Change									636		(636)
Net income, Change									32,163		(1,705)
Pretax operating income, Change %									3.00%		1.00%
Applicable taxes, Change %									4.00%		(2.00%)
After-tax total net operating income, before discontinued operations, Change %									3.00%		3.00%
Net operating income, change percent									3.00%		(3.00%)
Net income, Change %									6.00%		0.00%
Life Insurance
Segment Reporting Information [Line Items]
Pretax operating income									509,476		460,963		430,262
Pretax operating income, Change									48,513		30,701
Pretax operating income, Change %									11.00%		7.00%
Health Insurance
Segment Reporting Information [Line Items]
Pretax operating income									197,341		188,990		198,966
Pretax operating income, Change									8,351		(9,976)
Pretax operating income, Change %									4.00%		(5.00%)
Annuity
Segment Reporting Information [Line Items]
Pretax operating income									3,465		2,345		1,348
Pretax operating income, Change									1,120		997
Pretax operating income, Change %									48.00%
Other Income
Segment Reporting Information [Line Items]
Pretax operating income									1,898		2,507		2,834
Pretax operating income, Change									(609)		(327)
Pretax operating income, Change %									(24.00%)		(12.00%)
Administrative Expense
Segment Reporting Information [Line Items]
Pretax operating income									(165,405)		(159,109)		(155,615)
Pretax operating income, Change									(6,296)		(3,494)
Pretax operating income, Change %									4.00%		2.00%
Investment
Segment Reporting Information [Line Items]
Pretax operating income									236,644		258,986		265,245
Pretax operating income, Change									(22,342)		(6,259)
Pretax operating income, Change %									(9.00%)		(2.00%)
Corporate And Adjustments
Segment Reporting Information [Line Items]
Pretax operating income									(29,827)		(22,647)		(20,657)
Pretax operating income, Change									$ (7,180)		$ (1,990)
Pretax operating income, Change %									32.00%		10.00%

[1] See the discussion of Realized Gains and Losses in this report.