Condensed Consolidated Statements of Earnings (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Premiums and other revenues:
Universal life and annuity contract charges	$ 36,924	$ 34,550	$ 109,776	$ 97,014
Traditional life premiums	4,124	4,685	13,111	13,314
Net investment income	139,074	44,538	366,813	275,777
Other revenues	5,923	5,643	17,444	20,247
Net realized investment gains (losses):
Total other-than-temporary impairment (“OTTI”) gains (losses)	1,250	(1,741)	788	(1,741)
Portion of OTTI (gains) losses recognized in other comprehensive income	(1,761)	1,719	(1,918)	1,719
Net OTTI losses recognized in earnings	(511)	(22)	(1,130)	(22)
Other net investment gains (losses)	5,451	2,960	9,242	6,542
Total net realized investment gains (losses)	4,940	2,938	8,112	6,520
Total revenues	190,985	92,354	515,256	412,872
Benefits and expenses:
Life and other policy benefits	12,323	12,363	39,858	34,177
Amortization of deferred policy acquisition costs	28,403	29,909	91,463	96,246
Universal life and annuity contract interest	89,386	1,873	216,933	147,254
Other operating expenses	22,143	18,948	64,613	58,727
Total benefits and expenses	152,255	63,093	412,867	336,404
Earnings before Federal income taxes	38,730	29,261	102,389	76,468
Federal income taxes	14,408	9,996	35,080	25,203
Net earnings	24,322	19,265	67,309	51,265
Common Class A [Member]
Benefits and expenses:
Net earnings	23,634	18,720	65,405	49,815
Basic earnings per share:
Earnings Per Share, Basic (in dollars per share)	$ 6.88	$ 5.45	$ 19.04	$ 14.51
Diluted earnings per share:
Earnings Per Share, Diluted (in dollars per share)	$ 6.88	$ 5.45	$ 19.04	$ 14.49
Common Class B [Member]
Benefits and expenses:
Net earnings	$ 688	$ 545	$ 1,904	$ 1,450
Basic earnings per share:
Earnings Per Share, Basic (in dollars per share)	$ 3.44	$ 2.73	$ 9.52	$ 7.25
Diluted earnings per share:
Earnings Per Share, Diluted (in dollars per share)	$ 3.44	$ 2.73	$ 9.52	$ 7.25