Consolidated Statements of Earnings (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Premiums and other revenue:
Universal life and annuity contract charges	$ 149,328	$ 132,133	$ 127,192
Traditional life premiums	18,616	18,078	16,565
Net investment income	460,048	391,034	401,383
Other revenues	23,470	25,439	25,377
Net realized investment gains (losses):
Total other-than-temporary impairment (“OTTI”) losses	1,023	(1,752)	(729)
Portion of OTTI losses recognized in other comprehensive income	(2,364)	1,613	0
Net OTTI losses recognized in earnings	(1,341)	(139)	(729)
Other net investment gains	14,541	6,202	6,204
Realized gains (losses) on investments	13,200	6,063	5,475
Total revenues	664,662	572,747	575,992
Benefits and expenses:
Life and other policy benefits	51,842	46,494	52,929
Deferred Policy Acquisition Cost, Amortization Expense	121,922	133,088	96,449
Universal life and annuity contract interest	262,339	232,788	266,603
Other operating expenses	87,978	77,541	55,448
Total benefits and expenses	524,081	489,911	471,429
Earnings before Federal income taxes	140,581	82,836	104,563
Federal income taxes	48,023	27,209	31,666
Net earnings	92,558	55,627	72,897
Common Class A [Member]
Benefits and expenses:
Net earnings	89,940	54,053	70,832
Basic Earnings Per Share:
Earnings Per Share, Basic (in dollars per share)	$ 26.19	$ 15.74	$ 20.67
Diluted Earnings Per Share:
Earnings Per Share, Diluted (in dollars per share)	$ 26.19	$ 15.73	$ 20.61
Common Class B [Member]
Benefits and expenses:
Net earnings	$ 2,618	$ 1,574	$ 2,065
Basic Earnings Per Share:
Earnings Per Share, Basic (in dollars per share)	$ 13.09	$ 7.87	$ 10.33
Diluted Earnings Per Share:
Earnings Per Share, Diluted (in dollars per share)	$ 13.09	$ 7.87	$ 10.33