Fair Values of Financial Instruments - Schedule of Carrying Amounts and Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
ASSETS
Debt securities, available-for-sale	$ 9,068,946	$ 10,770,923
Debt securities, trading	1,077,438	0
Mortgage loans	8,469	0
Derivatives, index options	101,622	132,821
Equity securities	28,217	17,744
Carrying Values
ASSETS
Debt securities, available-for-sale	9,068,946	10,770,923
Debt securities, trading	1,077,438
Cash and cash equivalents	714,624	581,059
Mortgage loans	487,304	332,521
Real estate	28,606	33,783
Policy loans	71,286	74,083
Other loans	24,266	23,396
Derivatives, index options	101,622	132,821
Equity securities	28,217	17,744
Life interest in Libbie Shearn Moody Trust	8,254	9,083
Other investments	4,537	4,513
LIABILITIES
Deferred annuity contracts	6,463,314	6,662,730
Immediate annuity and supplemental contracts	422,209	412,526
Fair Values
ASSETS
Debt securities, available-for-sale	9,068,946	10,770,923
Debt securities, trading	1,077,438
Cash and cash equivalents	714,624	581,059
Mortgage loans	513,246	348,175
Real estate	47,027	48,577
Policy loans	110,492	121,260
Other loans	25,085	23,691
Derivatives, index options	101,622	132,821
Equity securities	28,217	17,744
Life interest in Libbie Shearn Moody Trust	12,775	12,775
Other investments	24,876	22,580
LIABILITIES
Deferred annuity contracts	4,703,331	5,192,663
Immediate annuity and supplemental contracts	457,787	467,538
Level 1
ASSETS
Debt securities, available-for-sale	0	0
Debt securities, trading	0
Cash and cash equivalents	702,632	581,059
Mortgage loans	0	0
Real estate	0	0
Policy loans	0	0
Other loans	0	0
Derivatives, index options	0	0
Equity securities	23,795	17,744
Life interest in Libbie Shearn Moody Trust	0	0
Other investments	0	0
LIABILITIES
Deferred annuity contracts	0	0
Immediate annuity and supplemental contracts	0	0
Level 2
ASSETS
Debt securities, available-for-sale	8,741,984	10,770,923
Debt securities, trading	1,002,616
Cash and cash equivalents	11,992	0
Mortgage loans	0	0
Real estate	0	0
Policy loans	0	0
Other loans	0	0
Derivatives, index options	0	0
Equity securities	4,422	0
Life interest in Libbie Shearn Moody Trust	0	0
Other investments	0	0
LIABILITIES
Deferred annuity contracts	0	0
Immediate annuity and supplemental contracts	0	0
Level 3
ASSETS
Debt securities, available-for-sale	326,962	0
Debt securities, trading	74,822
Cash and cash equivalents	0	0
Mortgage loans	513,246	348,175
Real estate	47,027	48,577
Policy loans	110,492	121,260
Other loans	25,085	23,691
Derivatives, index options	101,622	132,821
Equity securities	0	0
Life interest in Libbie Shearn Moody Trust	12,775	12,775
Other investments	24,876	22,580
LIABILITIES
Deferred annuity contracts	4,703,331	5,192,663
Immediate annuity and supplemental contracts	$ 457,787	$ 467,538

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