Condensed Consolidated Statements of Earnings (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Premiums and other revenues:
Universal life and annuity contract charges	$ 37,899	$ 36,199
Traditional life premiums	3,864	4,083
Net investment income	180,814	149,558
Other revenues	6,142	5,655
Net realized investment gains (losses):
Total other-than-temporary impairment (“OTTI”) gains (losses)	382	(277)
Portion of OTTI (gains) losses recognized in other comprehensive income	(443)	78
Net OTTI losses recognized in earnings	(61)	(199)
Other net investment gains (losses)	2,374	1,366
Total net realized investment gains (losses)	2,313	1,167
Total revenues	231,032	196,662
Benefits and expenses:
Life and other policy benefits	12,690	13,678
Amortization of deferred policy acquisition costs	30,804	31,711
Universal life and annuity contract interest	140,300	101,543
Other operating expenses	21,924	20,018
Total benefits and expenses	205,718	166,950
Earnings before Federal income taxes	25,314	29,712
Federal income taxes	8,682	9,971
Net earnings	16,632	19,741
Common Class A [Member]
Benefits and expenses:
Net earnings	16,162	19,183
Basic earnings per share:
Earnings Per Share, Basic (in dollars per share)	$ 4.71	$ 5.58
Diluted earnings per share:
Earnings Per Share, Diluted (in dollars per share)	$ 4.70	$ 5.58
Common Class B [Member]
Benefits and expenses:
Net earnings	$ 470	$ 558
Basic earnings per share:
Earnings Per Share, Basic (in dollars per share)	$ 2.35	$ 2.79
Diluted earnings per share:
Earnings Per Share, Diluted (in dollars per share)	$ 2.35	$ 2.79