Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Investments:
Securities held to maturity, at amortized cost (fair value: $6,125,668 and $6,082,330)	$ 5,673,932	$ 5,641,909
Securities available for sale, at fair value (cost: $2,527,082 and $2,422,650)	2,738,151	2,624,953
Mortgage loans, net of allowance for possible losses ($4,571 and $4,571)	153,394	157,460
Policy loans	74,649	74,967
Derivatives, index options	83,693	30,844
Other long-term investments	44,311	34,472
Total investments	8,768,130	8,564,605
Cash and short-term investments	75,491	119,290
Deferred policy acquisition costs	713,377	722,542
Deferred sales inducements	155,222	155,753
Accrued investment income	92,075	87,875
Federal income tax receivable	0	0
Other assets	80,310	77,934
Total assets	9,884,605	9,727,999
Future policy benefits:
Universal life and annuity contracts	8,126,345	8,023,798
Traditional life and annuity contracts	138,842	139,657
Other policyholder liabilities	150,568	151,308
Deferred Federal income tax liability	36,217	46,481
Federal income tax payable	23,125	5,962
Other liabilities	105,684	84,008
Total liabilities	8,580,781	8,451,214
COMMITMENTS AND CONTINGENCIES (Note 8)
Common stock:
Additional paid-in capital	37,767	37,767
Accumulated other comprehensive income	60,474	53,176
Retained earnings	1,201,948	1,182,207
Total stockholders’ equity	1,303,824	1,276,785
Total liabilities and stockholders' equity	9,884,605	9,727,999
Common Class A [Member]
Common stock:
Common stock, value outstanding	3,435	3,435
Common Class B [Member]
Common stock:
Common stock, value outstanding	$ 200	$ 200