Segment and Other Operating Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Selected Condensed Consolidated Balance Sheet Items:
Total segment assets	$ 11,462,003	$ 10,912,617	$ 11,351,892
Other policyholder liabilities	153,389		139,222
Condensed Consolidated Income Statements:
Premiums and contract revenues	41,660	42,276
Net investment income	99,923	108,451
Other revenues	5,329	5,763
Realized gains (losses) on investments	978	1,513
Total condensed consolidated premiums and other revenues	147,890	158,003
Life and other policy benefits	19,266	12,963
Amortization of deferred acquisition costs	27,652	28,579
Universal life and annuity contract interest	49,039	62,936
Other operating expenses	20,510	23,463
Federal income taxes (benefit)	9,755	9,706
Taxes on realized gains (losses) on investments	342	530
Total condensed consolidated Federal income taxes	10,097	10,236
Segment earnings (loss)	20,690	18,843
Realized gains (losses) on investments, net of taxes	636	983
Net earnings	21,326	19,826
Segments [Member]
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs and sales inducements	945,344	937,779
Total segment assets	11,278,305	10,714,485
Future policy benefits	9,542,267	9,157,868
Other policyholder liabilities	153,389	143,738
Condensed Consolidated Income Statements:
Premiums and contract revenues	41,660	42,276
Net investment income	99,923	108,451
Other revenues	5,329	5,763
Total condensed consolidated premiums and other revenues	146,912	156,490
Life and other policy benefits	19,266	12,963
Amortization of deferred acquisition costs	27,652	28,579
Universal life and annuity contract interest	49,039	62,936
Other operating expenses	20,510	23,463
Federal income taxes (benefit)	9,755	9,706
Total expenses	126,222	137,647
Segment earnings (loss)	20,690	18,843
Segments [Member] | Domestic Life Insurance [Member]
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs and sales inducements	65,368	53,815
Total segment assets	783,839	634,334
Future policy benefits	675,837	554,247
Other policyholder liabilities	13,661	11,867
Condensed Consolidated Income Statements:
Premiums and contract revenues	6,487	8,165
Net investment income	7,165	6,283
Other revenues	16	18
Total condensed consolidated premiums and other revenues	13,668	14,466
Life and other policy benefits	5,113	2,492
Amortization of deferred acquisition costs	3,181	2,400
Universal life and annuity contract interest	4,939	5,105
Other operating expenses	3,715	4,279
Federal income taxes (benefit)	(1,051)	65
Total expenses	15,897	14,341
Segment earnings (loss)	(2,229)	125
Segments [Member] | International Life Insurance [Member]
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs and sales inducements	249,736	239,432
Total segment assets	1,246,906	1,188,473
Future policy benefits	949,876	920,665
Other policyholder liabilities	17,777	15,587
Condensed Consolidated Income Statements:
Premiums and contract revenues	30,333	29,108
Net investment income	8,614	10,718
Other revenues	86	241
Total condensed consolidated premiums and other revenues	39,033	40,067
Life and other policy benefits	6,205	5,035
Amortization of deferred acquisition costs	(650)	6,745
Universal life and annuity contract interest	7,130	10,205
Other operating expenses	5,922	7,025
Federal income taxes (benefit)	6,545	3,759
Total expenses	25,152	32,769
Segment earnings (loss)	13,881	7,298
Segments [Member] | Annuities [Member]
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs and sales inducements	630,240	644,532
Total segment assets	8,988,348	8,627,243
Future policy benefits	7,916,554	7,682,956
Other policyholder liabilities	121,951	116,284
Condensed Consolidated Income Statements:
Premiums and contract revenues	4,840	5,003
Net investment income	79,236	86,617
Other revenues	15	37
Total condensed consolidated premiums and other revenues	84,091	91,657
Life and other policy benefits	7,948	5,436
Amortization of deferred acquisition costs	25,121	19,434
Universal life and annuity contract interest	36,970	47,626
Other operating expenses	6,178	7,096
Federal income taxes (benefit)	2,523	4,102
Total expenses	78,740	83,694
Segment earnings (loss)	5,351	7,963
Segments [Member] | All Others [Member]
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs and sales inducements	0	0
Total segment assets	259,212	264,435
Future policy benefits	0	0
Other policyholder liabilities	0	0
Condensed Consolidated Income Statements:
Premiums and contract revenues	0	0
Net investment income	4,908	4,833
Other revenues	5,212	5,467
Total condensed consolidated premiums and other revenues	10,120	10,300
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	4,695	5,063
Federal income taxes (benefit)	1,738	1,780
Total expenses	6,433	6,843
Segment earnings (loss)	3,687	3,457
Other unallocated [Member]
Selected Condensed Consolidated Balance Sheet Items:
Total segment assets	$ 183,698	$ 198,132