Segment and Other Operating Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs and sales inducements	$ 864,002	$ 868,599
Total segment assets	10,321,396	9,817,389
Other unallocated assets	155,105	67,216
Future policy benefits	8,725,381	8,265,187
Other policyholder liabilities	155,482	150,568	148,561
Total condensed consolidated assets	10,476,501	9,884,605	10,263,858
Condensed Consolidated Income Statements:
Premiums and contract revenues	41,763	40,282
Net investment income	180,814	149,558
Other revenues	6,142	5,655
Realized gains (losses) on investments	2,313	1,167
Total revenues	231,032	196,662
Total revenues	228,719	195,495
Life and other policy benefits	12,690	13,678
Amortization of deferred acquisition costs	30,804	31,711
Universal life and annuity contract interest	140,300	101,543
Other operating expenses	21,924	20,018
Federal income taxes (benefit)	7,872	9,563
Taxes on realized gains (losses) on investments	810	408
Total condensed consolidated Federal income taxes	8,682	9,971
Total expenses	213,590	176,513
Segment earnings (loss)	15,129	18,982
Realized gains (losses) on investments, net of taxes	1,503	759
Net earnings	16,632	19,741
Domestic Life Insurance [Member]
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs and sales inducements	41,026	36,432
Total segment assets	496,778	413,630
Future policy benefits	427,006	351,915
Other policyholder liabilities	12,547	10,738
Condensed Consolidated Income Statements:
Premiums and contract revenues	9,610	10,539
Net investment income	7,773	5,818
Other revenues	12	7
Total revenues	17,395	16,364
Life and other policy benefits	3,030	1,648
Amortization of deferred acquisition costs	2,035	2,391
Universal life and annuity contract interest	7,191	7,213
Other operating expenses	3,767	4,768
Federal income taxes (benefit)	470	115
Total expenses	16,493	16,135
Segment earnings (loss)	902	229
International Life Insurance [Member]
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs and sales inducements	227,263	230,753
Total segment assets	1,148,773	1,076,573
Future policy benefits	861,854	796,354
Other policyholder liabilities	10,139	18,457
Condensed Consolidated Income Statements:
Premiums and contract revenues	28,019	23,431
Net investment income	18,630	15,397
Other revenues	43	32
Total revenues	46,692	38,860
Life and other policy benefits	3,645	3,480
Amortization of deferred acquisition costs	5,787	5,608
Universal life and annuity contract interest	21,991	14,812
Other operating expenses	6,708	5,818
Federal income taxes (benefit)	2,930	3,063
Total expenses	41,061	32,781
Segment earnings (loss)	5,631	6,079
Annuities [Member]
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs and sales inducements	595,713	601,414
Total segment assets	8,418,536	8,100,477
Future policy benefits	7,436,521	7,116,918
Other policyholder liabilities	132,796	121,373
Condensed Consolidated Income Statements:
Premiums and contract revenues	4,134	6,312
Net investment income	150,378	124,389
Other revenues	39	61
Total revenues	154,551	130,762
Life and other policy benefits	6,015	8,550
Amortization of deferred acquisition costs	22,982	23,712
Universal life and annuity contract interest	111,118	79,518
Other operating expenses	6,086	4,028
Federal income taxes (benefit)	2,857	5,010
Total expenses	149,058	120,818
Segment earnings (loss)	5,493	9,944
All Others [Member]
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs and sales inducements	0	0
Total segment assets	257,309	226,709
Future policy benefits	0	0
Other policyholder liabilities	0	0
Condensed Consolidated Income Statements:
Premiums and contract revenues	0	0
Net investment income	4,033	3,954
Other revenues	6,048	5,555
Total revenues	10,081	9,509
Life and other policy benefits	0	0
Amortization of deferred acquisition costs	0	0
Universal life and annuity contract interest	0	0
Other operating expenses	5,363	5,404
Federal income taxes (benefit)	1,615	1,375
Total expenses	6,978	6,779
Segment earnings (loss)	$ 3,103	$ 2,730