Segment and Other Operating Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Selected Condensed Consolidated Balance Sheet Items:
Total segment assets	$ 11,259,076	$ 10,668,468	$ 11,259,076	$ 10,668,468	$ 10,830,416
Other policyholder liabilities	142,175		142,175		142,587
Condensed Consolidated Income Statements:
Premiums and contract revenues	41,108	37,682	126,770	125,026
Net investment income	110,966	141,403	374,596	451,904
Other revenues	5,377	5,822	16,351	17,954
Realized gains (losses) on investments	2,169	3,285	6,747	7,199
Total condensed consolidated premiums and other revenues	159,620	188,192	524,464	602,083
Life and other policy benefits	13,163	16,941	40,922	48,081
Amortization of deferred acquisition costs	23,467	24,244	79,304	83,900
Universal life and annuity contract interest	59,211	87,486	224,576	299,224
Other operating expenses	20,451	22,675	63,414	69,442
Federal income taxes (benefit)	14,102	10,913	36,411	30,511
Taxes on realized gains (losses) on investments	760	1,151	2,362	2,520
Total condensed consolidated Federal income taxes	14,862	12,064	38,773	33,031
Segment earnings (loss)	27,057	22,648	73,090	63,726
Realized gains (losses) on investments, net of taxes	1,409	2,134	4,385	4,679
Net earnings	28,466	24,782	77,475	68,405
Segments [Member]
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs and sales inducements	956,066	936,515	956,066	936,515
Total segment assets	11,051,908	10,462,353	11,051,908	10,462,353
Future policy benefits	9,404,645	8,934,285	9,404,645	8,934,285
Other policyholder liabilities	142,175	159,822	142,175	159,822
Condensed Consolidated Income Statements:
Premiums and contract revenues	41,108	37,682	126,770	125,026
Net investment income	110,966	141,403	374,596	451,904
Other revenues	5,377	5,822	16,351	17,954
Total condensed consolidated premiums and other revenues	157,451	184,907	517,717	594,884
Life and other policy benefits	13,163	16,941	40,922	48,081
Amortization of deferred acquisition costs	23,467	24,244	79,304	83,900
Universal life and annuity contract interest	59,211	87,486	224,576	299,224
Other operating expenses	20,451	22,675	63,414	69,442
Federal income taxes (benefit)	14,102	10,913	36,411	30,511
Total expenses	130,394	162,259	444,627	531,158
Segment earnings (loss)	27,057	22,648	73,090	63,726
Segments [Member] | Domestic Life Insurance [Member]
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs and sales inducements	61,087	50,067	61,087	50,067
Total segment assets	705,156	559,824	705,156	559,824
Future policy benefits	611,550	485,754	611,550	485,754
Other policyholder liabilities	12,742	13,177	12,742	13,177
Condensed Consolidated Income Statements:
Premiums and contract revenues	6,847	3,944	22,077	22,967
Net investment income	6,859	6,928	24,044	22,943
Other revenues	19	12	40	21
Total condensed consolidated premiums and other revenues	13,725	10,884	46,161	45,931
Life and other policy benefits	3,353	4,003	7,268	8,129
Amortization of deferred acquisition costs	1,166	1,015	5,346	5,260
Universal life and annuity contract interest	5,803	2,261	19,066	17,320
Other operating expenses	2,314	2,782	10,585	11,496
Federal income taxes (benefit)	379	268	1,295	1,206
Total expenses	13,015	10,329	43,560	43,411
Segment earnings (loss)	710	555	2,601	2,520
Segments [Member] | International Life Insurance [Member]
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs and sales inducements	242,124	235,922	242,124	235,922
Total segment assets	1,223,571	1,161,517	1,223,571	1,161,517
Future policy benefits	944,505	899,090	944,505	899,090
Other policyholder liabilities	12,226	16,778	12,226	16,778
Condensed Consolidated Income Statements:
Premiums and contract revenues	29,135	28,865	87,906	87,061
Net investment income	8,273	10,957	35,902	43,224
Other revenues	20	60	321	211
Total condensed consolidated premiums and other revenues	37,428	39,882	124,129	130,496
Life and other policy benefits	9,672	11,040	16,375	17,910
Amortization of deferred acquisition costs	2,525	3,287	18,078	17,000
Universal life and annuity contract interest	6,956	8,525	32,820	39,760
Other operating expenses	6,307	5,987	18,167	18,820
Federal income taxes (benefit)	4,143	3,596	12,865	11,982
Total expenses	29,603	32,435	98,305	105,472
Segment earnings (loss)	7,825	7,447	25,824	25,024
Segments [Member] | Annuities [Member]
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs and sales inducements	652,855	650,526	652,855	650,526
Total segment assets	8,871,276	8,487,915	8,871,276	8,487,915
Future policy benefits	7,848,590	7,549,441	7,848,590	7,549,441
Other policyholder liabilities	117,207	129,867	117,207	129,867
Condensed Consolidated Income Statements:
Premiums and contract revenues	5,126	4,873	16,787	14,998
Net investment income	90,835	118,521	300,118	371,704
Other revenues	23	22	63	52
Total condensed consolidated premiums and other revenues	95,984	123,416	316,968	386,754
Life and other policy benefits	138	1,898	17,279	22,042
Amortization of deferred acquisition costs	19,776	19,942	55,880	61,640
Universal life and annuity contract interest	46,452	76,700	172,690	242,144
Other operating expenses	7,045	8,565	19,965	23,117
Federal income taxes (benefit)	7,681	5,298	17,010	12,242
Total expenses	81,092	112,403	282,824	361,185
Segment earnings (loss)	14,892	11,013	34,144	25,569
Segments [Member] | All Others [Member]
Selected Condensed Consolidated Balance Sheet Items:
Deferred policy acquisition costs and sales inducements	0	0	0	0
Total segment assets	251,905	253,097	251,905	253,097
Future policy benefits	0	0	0	0
Other policyholder liabilities	0	0	0	0
Condensed Consolidated Income Statements:
Premiums and contract revenues	0	0	0	0
Net investment income	4,999	4,997	14,532	14,033
Other revenues	5,315	5,728	15,927	17,670
Total condensed consolidated premiums and other revenues	10,314	10,725	30,459	31,703
Life and other policy benefits	0	0	0	0
Amortization of deferred acquisition costs	0	0	0	0
Universal life and annuity contract interest	0	0	0	0
Other operating expenses	4,785	5,341	14,697	16,009
Federal income taxes (benefit)	1,899	1,751	5,241	5,081
Total expenses	6,684	7,092	19,938	21,090
Segment earnings (loss)	3,630	3,633	10,521	10,613
Other unallocated [Member]
Selected Condensed Consolidated Balance Sheet Items:
Total segment assets	$ 207,168	$ 206,115	$ 207,168	$ 206,115