Fair Values of Financial Instruments (Fair Value by Balance Sheet Grouping) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities held to maturity	$ 7,175,443	$ 6,656,144
Securities available for sale	2,728,680us-gaap_AvailableForSaleSecurities	2,651,544us-gaap_AvailableForSaleSecurities
Derivatives, index options	114,287us-gaap_DerivativeAssets	169,314us-gaap_DerivativeAssets
Carrying Values [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities held to maturity	6,841,543	6,510,320
Securities available for sale	2,728,680	2,651,544
Cash and cash equivalents	277,078	120,859
Mortgage loans	149,503	132,765
Policy loans	63,645	65,969
Other loans	2,171	2,986
Derivatives, index options	114,287	169,314
Life interest in Libbie Shearn Moody Trust	0	0
Deferred annuity contracts	7,546,504	7,288,861
Immediate annuity and supplemental contracts	446,458	463,276
Fair Values [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities held to maturity	7,175,443	6,656,144
Securities available for sale	2,728,680	2,651,544
Cash and cash equivalents	277,078	120,859
Mortgage loans	156,548	138,159
Policy loans	111,040	98,010
Other loans	2,300	3,143
Derivatives, index options	114,287	169,314
Life interest in Libbie Shearn Moody Trust	12,775	12,775
Deferred annuity contracts	7,178,535	6,941,902
Immediate annuity and supplemental contracts	474,843	483,690
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities held to maturity		0
Securities available for sale	16,862	13,802
Cash and cash equivalents	277,078	120,859
Mortgage loans	0	0
Policy loans	0	0
Other loans	0	0
Derivatives, index options	0	0
Life interest in Libbie Shearn Moody Trust	0	0
Deferred annuity contracts	0	0
Immediate annuity and supplemental contracts	0	0
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities held to maturity	7,175,443	6,656,144
Securities available for sale	2,711,818	2,637,742
Cash and cash equivalents	0	0
Mortgage loans	0	0
Policy loans	0	0
Other loans	0	0
Derivatives, index options	0	0
Life interest in Libbie Shearn Moody Trust	0	0
Deferred annuity contracts	0	0
Immediate annuity and supplemental contracts	0	0
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities held to maturity	0	0
Securities available for sale	0	0
Cash and cash equivalents	0	0
Mortgage loans	156,548	138,159
Policy loans	111,040	98,010
Other loans	2,300	3,143
Derivatives, index options	114,287	169,314
Life interest in Libbie Shearn Moody Trust	12,775	12,775
Deferred annuity contracts	7,178,535	6,941,902
Immediate annuity and supplemental contracts	$ 474,843	$ 483,690

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Fair value of investments in debt securities classified as held-to-maturity.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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