Fair Value - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Assets
Available-for-sale securities	$ 74,735	$ 71,374
Trading securities	2,075	2,070
Equity securities	237	247
Mortgage loans	15,203	14,306
Funds withheld at interest	42,269	15,181
Derivative assets	2,379	2,888
Other investments	359	158
Restricted cash	1,281	402
Reinsurance recoverable	5,310	4,863
Liabilities
Interest sensitive contract liabilities	135,537	102,745
Future policy benefits	24,596	23,330
Derivative liabilities	118	97
Funds withheld liability	427	408
Related Party
Assets
Available-for-sale securities	4,070	3,804
Trading securities	872	785
Equity securities	52	64
Mortgage loans	626	653
Funds withheld at interest	12,971	13,220
Other investments	474	487
Liabilities
Interest sensitive contract liabilities	14,609	15,285
Future policy benefits	1,446	1,302
Funds withheld liability	0	0
U.S. government and agencies
Assets
Available-for-sale securities	74	36
U.S. state, municipal and political subdivisions
Assets
Available-for-sale securities	943	1,541
Foreign governments
Assets
Available-for-sale securities	337	327
Corporate
Assets
Available-for-sale securities	51,199	47,228
Corporate | Related Party
Assets
Available-for-sale securities	20	19
CLO
Assets
Available-for-sale securities	7,952	7,349
CLO | Related Party
Assets
Available-for-sale securities	1,239	936
ABS
Assets
Available-for-sale securities	4,773	5,118
ABS | Related Party
Assets
Available-for-sale securities	2,811	2,849
CMBS
Assets
Available-for-sale securities	2,297	2,400
RMBS
Assets
Available-for-sale securities	7,160	7,375
Level 3
Assets
Available-for-sale securities	3,582	1,289
Recurring
Assets
Investment funds		819
Recurring | Level 1
Assets
Available-for-sale securities	74	36
Trading securities	8	8
Equity securities	28	43
Mortgage loans	0	0
Investment funds	0	0
Derivative assets	81	10
Short-term investments	43	46
Other investments	0	0
Cash and cash equivalents	6,240	4,240
Restricted cash	1,281	402
Reinsurance recoverable	0	0
Total assets measured at fair value	7,755	4,785
Liabilities
Derivative liabilities	0	1
Total liabilities measured at fair value	0	1
Recurring | Level 1 | Related Party
Assets
Available-for-sale securities	0	0
Trading securities	0	0
Equity securities	0	0
Investment funds	0	0
Recurring | Level 1 | Universal life
Liabilities
Interest sensitive contract liabilities	0	0
Recurring | Level 1 | AmerUs Closed Block
Liabilities
Future policy benefits	0	0
Recurring | Level 1 | ILICO Closed Block and life benefits
Liabilities
Future policy benefits	0	0
Recurring | Level 1 | Embedded derivatives
Assets
Funds withheld at interest	0	0
Liabilities
Interest sensitive contract liabilities	0	0
Funds withheld liability	0	0
Recurring | Level 1 | Embedded derivatives | Related Party
Assets
Funds withheld at interest	0	0
Recurring | Level 1 | U.S. government and agencies
Assets
Available-for-sale securities	74	36
Trading securities	8	8
Recurring | Level 1 | U.S. state, municipal and political subdivisions
Assets
Available-for-sale securities	0	0
Trading securities	0	0
Recurring | Level 1 | Foreign governments
Assets
Available-for-sale securities	0	0
Recurring | Level 1 | Corporate
Assets
Available-for-sale securities	0	0
Trading securities	0	0
Recurring | Level 1 | Corporate | Related Party
Assets
Available-for-sale securities	0	0
Recurring | Level 1 | CLO
Assets
Available-for-sale securities	0	0
Trading securities	0	0
Recurring | Level 1 | CLO | Related Party
Assets
Available-for-sale securities	0	0
Trading securities	0	0
Recurring | Level 1 | ABS
Assets
Available-for-sale securities	0	0
Trading securities	0	0
Recurring | Level 1 | ABS | Related Party
Assets
Available-for-sale securities	0	0
Trading securities	0	0
Recurring | Level 1 | CMBS
Assets
Available-for-sale securities	0	0
Trading securities	0	0
Recurring | Level 1 | RMBS
Assets
Available-for-sale securities	0	0
Trading securities	0	0
Recurring | Level 2
Assets
Available-for-sale securities	72,654	69,032
Trading securities	2,003	1,988
Equity securities	203	201
Mortgage loans	0	0
Investment funds	0	0
Derivative assets	2,298	2,878
Short-term investments	207	319
Other investments	109	93
Cash and cash equivalents	0	0
Restricted cash	0	0
Reinsurance recoverable	0	0
Total assets measured at fair value	79,486	76,027
Liabilities
Derivative liabilities	46	93
Total liabilities measured at fair value	159	124
Recurring | Level 2 | Related Party
Assets
Available-for-sale securities	2,009	1,480
Trading securities	3	36
Equity securities	0	0
Investment funds	0	0
Recurring | Level 2 | Universal life
Liabilities
Interest sensitive contract liabilities	0	0
Recurring | Level 2 | AmerUs Closed Block
Liabilities
Future policy benefits	0	0
Recurring | Level 2 | ILICO Closed Block and life benefits
Liabilities
Future policy benefits	0	0
Recurring | Level 2 | Embedded derivatives
Assets
Funds withheld at interest	0	0
Liabilities
Interest sensitive contract liabilities	0	0
Funds withheld liability	113	31
Recurring | Level 2 | Embedded derivatives | Related Party
Assets
Funds withheld at interest	0	0
Recurring | Level 2 | U.S. government and agencies
Assets
Available-for-sale securities	0	0
Trading securities	3	3
Recurring | Level 2 | U.S. state, municipal and political subdivisions
Assets
Available-for-sale securities	903	1,501
Trading securities	114	135
Recurring | Level 2 | Foreign governments
Assets
Available-for-sale securities	337	327
Recurring | Level 2 | Corporate
Assets
Available-for-sale securities	50,325	46,503
Trading securities	1,537	1,456
Recurring | Level 2 | Corporate | Related Party
Assets
Available-for-sale securities	20	19
Recurring | Level 2 | CLO
Assets
Available-for-sale securities	7,792	7,228
Trading securities	0	0
Recurring | Level 2 | CLO | Related Party
Assets
Available-for-sale securities	1,239	936
Trading securities	3	36
Recurring | Level 2 | ABS
Assets
Available-for-sale securities	3,905	3,744
Trading securities	81	92
Recurring | Level 2 | ABS | Related Party
Assets
Available-for-sale securities	750	525
Trading securities	0	0
Recurring | Level 2 | CMBS
Assets
Available-for-sale securities	2,248	2,354
Trading securities	51	51
Recurring | Level 2 | RMBS
Assets
Available-for-sale securities	7,144	7,375
Trading securities	217	251
Recurring | Level 3
Assets
Available-for-sale securities	2,007	2,306
Trading securities	64	74
Equity securities	6	3
Mortgage loans	25	27
Investment funds	17	22
Derivative assets	0	0
Short-term investments	114	41
Other investments	0	0
Cash and cash equivalents	0	0
Restricted cash	0	0
Reinsurance recoverable	2,099	1,821
Total assets measured at fair value	10,447	8,958
Liabilities
Derivative liabilities	0	3
Total liabilities measured at fair value	14,802	14,296
Recurring | Level 3 | Related Party
Assets
Available-for-sale securities	2,061	2,324
Trading securities	869	749
Equity securities	52	64
Investment funds	1,810	132
Recurring | Level 3 | Universal life
Liabilities
Interest sensitive contract liabilities	1,323	1,050
Recurring | Level 3 | AmerUs Closed Block
Liabilities
Future policy benefits	1,573	1,546
Recurring | Level 3 | ILICO Closed Block and life benefits
Liabilities
Future policy benefits	761	755
Recurring | Level 3 | Embedded derivatives
Assets
Funds withheld at interest	763	801
Liabilities
Interest sensitive contract liabilities	11,140	10,942
Funds withheld liability	5	0
Recurring | Level 3 | Embedded derivatives | Related Party
Assets
Funds withheld at interest	560	594
Recurring | Level 3 | U.S. government and agencies
Assets
Available-for-sale securities	0	0
Trading securities	0	0
Recurring | Level 3 | U.S. state, municipal and political subdivisions
Assets
Available-for-sale securities	40	40
Trading securities	0	0
Recurring | Level 3 | Foreign governments
Assets
Available-for-sale securities	0	0
Recurring | Level 3 | Corporate
Assets
Available-for-sale securities	874	725
Trading securities	6	0
Recurring | Level 3 | Corporate | Related Party
Assets
Available-for-sale securities	0	0
Recurring | Level 3 | CLO
Assets
Available-for-sale securities	160	121
Trading securities	3	6
Recurring | Level 3 | CLO | Related Party
Assets
Available-for-sale securities	0	0
Trading securities	45	38
Recurring | Level 3 | ABS
Assets
Available-for-sale securities	868	1,374
Trading securities	0	16
Recurring | Level 3 | ABS | Related Party
Assets
Available-for-sale securities	2,061	2,324
Trading securities	824	711
Recurring | Level 3 | CMBS
Assets
Available-for-sale securities	49	46
Trading securities	0	0
Recurring | Level 3 | RMBS
Assets
Available-for-sale securities	16	0
Trading securities	55	52
Recurring | NAV
Assets
Investment funds	129	132
Total assets measured at fair value	204
Recurring | NAV | Related Party
Assets
Investment funds	75	687
Fair Value
Assets
Mortgage loans	15,636	14,719
Investment funds	536	596
Funds withheld at interest	41,506	14,380
Short-term investments		190
Other investments	256	65
Total assets measured at fair value	75,223	46,902
Liabilities
Interest sensitive contract liabilities	90,369	58,027
Funds withheld liability	381	377
Fair Value | Related Party
Assets
Mortgage loans	617	641
Investment funds	3,392	2,731
Funds withheld at interest	12,411	12,626
Other investments	476	537
Fair Value | Level 1
Assets
Mortgage loans	0	0
Investment funds	0	0
Funds withheld at interest	0	0
Short-term investments		0
Other investments	0	0
Total assets measured at fair value	0	0
Liabilities
Interest sensitive contract liabilities	0	0
Funds withheld liability	0	0
Fair Value | Level 1 | Related Party
Assets
Mortgage loans	0	0
Investment funds	0	0
Funds withheld at interest	0	0
Other investments	0	0
Fair Value | Level 2
Assets
Mortgage loans	0	0
Investment funds	0	0
Funds withheld at interest	0	0
Short-term investments		0
Other investments	0	0
Total assets measured at fair value	393	417
Liabilities
Interest sensitive contract liabilities	0	0
Funds withheld liability	381	377
Fair Value | Level 2 | Related Party
Assets
Mortgage loans	0	0
Investment funds	0	0
Funds withheld at interest	0	0
Other investments	0	0
Fair Value | Level 3
Assets
Mortgage loans	15,636	14,719
Investment funds	0	0
Funds withheld at interest	41,506	14,380
Short-term investments		190
Other investments	256	65
Total assets measured at fair value	70,902	43,158
Liabilities
Interest sensitive contract liabilities	90,369	58,027
Funds withheld liability	0	0
Fair Value | Level 3 | Related Party
Assets
Mortgage loans	617	641
Investment funds	0	0
Funds withheld at interest	12,411	12,626
Other investments	476	537
Fair Value | NAV
Assets
Investment funds	536	596
Total assets measured at fair value	3,928	3,327
Fair Value | NAV | Related Party
Assets
Investment funds	3,392	2,731
Fair Value | Recurring
Assets
Available-for-sale securities	74,735	71,374
Trading securities	2,075	2,070
Equity securities	237	247
Mortgage loans	25	27
Investment funds	146	154
Funds withheld at interest	763	801
Derivative assets	2,379	2,888
Short-term investments	364	406
Other investments	109	93
Cash and cash equivalents	6,240	4,240
Restricted cash	1,281	402
Reinsurance recoverable	2,099	1,821
Total assets measured at fair value	97,892	90,589
Liabilities
Interest sensitive contract liabilities	12,463	11,992
Future policy benefits	2,334	2,301
Derivative liabilities	118	97
Funds withheld liability	46	31
Total liabilities measured at fair value	14,961	14,421
Fair Value | Recurring | Related Party
Assets
Available-for-sale securities	4,070	3,804
Trading securities	872	785
Equity securities	52	64
Investment funds	1,885	819
Funds withheld at interest	560	594
Fair Value | Recurring | Universal life
Liabilities
Interest sensitive contract liabilities	1,323	1,050
Fair Value | Recurring | AmerUs Closed Block
Liabilities
Future policy benefits	1,573	1,546
Fair Value | Recurring | ILICO Closed Block and life benefits
Liabilities
Future policy benefits	761	755
Fair Value | Recurring | Embedded derivatives
Assets
Funds withheld at interest	763	801
Liabilities
Interest sensitive contract liabilities	11,140	10,942
Funds withheld liability	46	31
Fair Value | Recurring | Embedded derivatives | Related Party
Assets
Funds withheld at interest	560	594
Fair Value | Recurring | U.S. government and agencies
Assets
Available-for-sale securities	74	36
Trading securities	11	11
Fair Value | Recurring | U.S. state, municipal and political subdivisions
Assets
Available-for-sale securities	943	1,541
Trading securities	114	135
Fair Value | Recurring | Foreign governments
Assets
Available-for-sale securities	337	327
Fair Value | Recurring | Corporate
Assets
Available-for-sale securities	51,199	47,228
Trading securities	1,543	1,456
Fair Value | Recurring | Corporate | Related Party
Assets
Available-for-sale securities	20	19
Fair Value | Recurring | CLO
Assets
Available-for-sale securities	7,952	7,349
Trading securities	3	6
Fair Value | Recurring | CLO | Related Party
Assets
Available-for-sale securities	1,239	936
Trading securities	48	74
Fair Value | Recurring | ABS
Assets
Available-for-sale securities	4,773	5,118
Trading securities	81	108
Fair Value | Recurring | ABS | Related Party
Assets
Available-for-sale securities	2,811	2,849
Trading securities	824	711
Fair Value | Recurring | CMBS
Assets
Available-for-sale securities	2,297	2,400
Trading securities	51	51
Fair Value | Recurring | RMBS
Assets
Available-for-sale securities	7,160	7,375
Trading securities	$ 272	$ 303