Fair Value - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Assets
Available-for-sale securities	$ 73,988	$ 71,374
Trading securities	2,069	2,070
Mortgage loans	14,591	14,306
Investment funds	156	154
Funds withheld at interest	48,593	15,181
Derivative assets	2,771	2,888
Short-term investments	165	596
Other investments	949	158
Restricted cash	1,226	402
Reinsurance recoverable	5,104	4,863
Liabilities
Interest sensitive contract liabilities	141,207	102,745
Future policy benefits	24,823	23,330
Derivative liabilities	147	97
Funds withheld liability	440	408
Related Party
Assets
Available-for-sale securities	4,857	3,804
Trading securities	1,397	785
Equity securities	50	64
Mortgage loans	640	653
Investment funds	1,850	819
Funds withheld at interest	13,053	13,220
Other investments	467	487
Liabilities
Interest sensitive contract liabilities	14,352	15,285
Future policy benefits	1,527	1,302
U.S. government and agencies
Assets
Available-for-sale securities	73	36
U.S. state, municipal and political subdivisions
Assets
Available-for-sale securities	927	1,541
Foreign governments
Assets
Available-for-sale securities	340	327
Corporate
Assets
Available-for-sale securities	51,129	47,228
Corporate | Related Party
Assets
Available-for-sale securities	784	19
CLO
Assets
Available-for-sale securities	8,370	7,349
CLO | Related Party
Assets
Available-for-sale securities	1,344	936
ABS
Assets
Available-for-sale securities	4,200	5,118
ABS | Related Party
Assets
Available-for-sale securities	2,729	2,849
CMBS
Assets
Available-for-sale securities	2,239	2,400
RMBS
Assets
Available-for-sale securities	6,710	7,375
Level 3
Assets
Available-for-sale securities	5,468	1,289
Recurring
Assets
Investment funds		819
Recurring | Level 1
Assets
Available-for-sale securities	73	36
Trading securities	8	8
Equity securities	29	43
Mortgage loans	0	0
Investment funds	0	0
Derivative assets	48	10
Short-term investments	45	46
Other investments	0	0
Cash and cash equivalents	7,548	4,240
Restricted cash	1,226	402
Reinsurance recoverable	0	0
Total assets measured at fair value	8,977	4,785
Liabilities
Derivative liabilities	0	1
Total liabilities measured at fair value	5	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	5	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	73	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	71,740	69,032
Trading securities	1,958	1,988
Equity securities	220	201
Mortgage loans	0	0
Investment funds	0	0
Derivative assets	2,723	2,878
Short-term investments	110	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	78,903	76,027
Liabilities
Derivative liabilities	50	93
Total liabilities measured at fair value	187	124
Recurring | Level 2 | Related Party
Assets
Available-for-sale securities	2,019	1,480
Trading securities	24	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	137	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	893	1,501
Trading securities	115	135
Recurring | Level 2 | Foreign governments
Assets
Available-for-sale securities	339	327
Recurring | Level 2 | Corporate
Assets
Available-for-sale securities	50,229	46,503
Trading securities	1,526	1,456
Recurring | Level 2 | Corporate | Related Party
Assets
Available-for-sale securities	20	19
Recurring | Level 2 | CLO
Assets
Available-for-sale securities	8,179	7,228
Trading securities	0	0
Recurring | Level 2 | CLO | Related Party
Assets
Available-for-sale securities	1,333	936
Trading securities	24	36
Recurring | Level 2 | ABS
Assets
Available-for-sale securities	3,221	3,744
Trading securities	84	92
Recurring | Level 2 | ABS | Related Party
Assets
Available-for-sale securities	666	525
Trading securities	0	0
Recurring | Level 2 | CMBS
Assets
Available-for-sale securities	2,169	2,354
Trading securities	52	51
Recurring | Level 2 | RMBS
Assets
Available-for-sale securities	6,710	7,375
Trading securities	178	251
Recurring | Level 3
Assets
Available-for-sale securities	2,175	2,306
Trading securities	103	74
Equity securities	16	3
Mortgage loans	19	27
Investment funds	17	22
Derivative assets	0	0
Short-term investments	10	41
Other investments	0	0
Cash and cash equivalents	0	0
Restricted cash	0	0
Reinsurance recoverable	2,155	1,821
Total assets measured at fair value	12,506	8,958
Liabilities
Derivative liabilities	0	3
Total liabilities measured at fair value	15,463	14,296
Recurring | Level 3 | Related Party
Assets
Available-for-sale securities	2,838	2,324
Trading securities	1,373	749
Equity securities	50	64
Investment funds	1,770	132
Recurring | Level 3 | Universal life
Liabilities
Interest sensitive contract liabilities	1,363	1,050
Recurring | Level 3 | AmerUs Closed Block
Liabilities
Future policy benefits	1,577	1,546
Recurring | Level 3 | ILICO Closed Block and life benefits
Liabilities
Future policy benefits	777	755
Recurring | Level 3 | Embedded derivatives
Assets
Funds withheld at interest	1,259	801
Liabilities
Interest sensitive contract liabilities	11,741	10,942
Funds withheld liability	5	0
Recurring | Level 3 | Embedded derivatives | Related Party
Assets
Funds withheld at interest	721	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	34	40
Trading securities	0	0
Recurring | Level 3 | Foreign governments
Assets
Available-for-sale securities	1	0
Recurring | Level 3 | Corporate
Assets
Available-for-sale securities	900	725
Trading securities	6	0
Recurring | Level 3 | Corporate | Related Party
Assets
Available-for-sale securities	764	0
Recurring | Level 3 | CLO
Assets
Available-for-sale securities	191	121
Trading securities	3	6
Recurring | Level 3 | CLO | Related Party
Assets
Available-for-sale securities	11	0
Trading securities	28	38
Recurring | Level 3 | ABS
Assets
Available-for-sale securities	979	1,374
Trading securities	35	16
Recurring | Level 3 | ABS | Related Party
Assets
Available-for-sale securities	2,063	2,324
Trading securities	1,345	711
Recurring | Level 3 | CMBS
Assets
Available-for-sale securities	70	46
Trading securities	0	0
Recurring | Level 3 | RMBS
Assets
Available-for-sale securities	0	0
Trading securities	59	52
Recurring | NAV
Assets
Investment funds	139	132
Total assets measured at fair value	219
Recurring | NAV | Related Party
Assets
Investment funds	80	687
Fair Value
Assets
Mortgage loans	15,114	14,719
Investment funds	567	596
Funds withheld at interest	47,334	14,380
Short-term investments		190
Other investments	852	65
Total assets measured at fair value	80,661	46,902
Liabilities
Interest sensitive contract liabilities	96,125	58,027
Funds withheld liability	390	377
Fair Value | Related Party
Assets
Mortgage loans	628	641
Investment funds	2,958	2,731
Funds withheld at interest	12,332	12,626
Other investments	489	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	387	417
Liabilities
Interest sensitive contract liabilities	0	0
Funds withheld liability	390	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	15,114	14,719
Investment funds	0	0
Funds withheld at interest	47,334	14,380
Short-term investments		190
Other investments	852	65
Total assets measured at fair value	76,749	43,158
Liabilities
Interest sensitive contract liabilities	96,125	58,027
Funds withheld liability	0	0
Fair Value | Level 3 | Related Party
Assets
Mortgage loans	628	641
Investment funds	0	0
Funds withheld at interest	12,332	12,626
Other investments	489	537
Fair Value | NAV
Assets
Investment funds	567	596
Total assets measured at fair value	3,525	3,327
Fair Value | NAV | Related Party
Assets
Investment funds	2,958	2,731
Fair Value | Recurring
Assets
Available-for-sale securities	73,988	71,374
Trading securities	2,069	2,070
Equity securities	265	247
Mortgage loans	19	27
Investment funds	156	154
Funds withheld at interest	1,259	801
Derivative assets	2,771	2,888
Short-term investments	165	406
Other investments	109	93
Cash and cash equivalents	7,548	4,240
Restricted cash	1,226	402
Reinsurance recoverable	2,155	1,821
Total assets measured at fair value	100,605	90,589
Liabilities
Interest sensitive contract liabilities	13,104	11,992
Future policy benefits	2,354	2,301
Derivative liabilities	147	97
Funds withheld liability	50	31
Total liabilities measured at fair value	15,655	14,421
Fair Value | Recurring | Related Party
Assets
Available-for-sale securities	4,857	3,804
Trading securities	1,397	785
Equity securities	50	64
Investment funds	1,850	819
Funds withheld at interest	721	594
Fair Value | Recurring | Universal life
Liabilities
Interest sensitive contract liabilities	1,363	1,050
Fair Value | Recurring | AmerUs Closed Block
Liabilities
Future policy benefits	1,577	1,546
Fair Value | Recurring | ILICO Closed Block and life benefits
Liabilities
Future policy benefits	777	755
Fair Value | Recurring | Embedded derivatives
Assets
Funds withheld at interest	1,259	801
Liabilities
Interest sensitive contract liabilities	11,741	10,942
Funds withheld liability	50	31
Fair Value | Recurring | Embedded derivatives | Related Party
Assets
Funds withheld at interest	721	594
Fair Value | Recurring | U.S. government and agencies
Assets
Available-for-sale securities	73	36
Trading securities	11	11
Fair Value | Recurring | U.S. state, municipal and political subdivisions
Assets
Available-for-sale securities	927	1,541
Trading securities	115	135
Fair Value | Recurring | Foreign governments
Assets
Available-for-sale securities	340	327
Fair Value | Recurring | Corporate
Assets
Available-for-sale securities	51,129	47,228
Trading securities	1,532	1,456
Fair Value | Recurring | Corporate | Related Party
Assets
Available-for-sale securities	784	19
Fair Value | Recurring | CLO
Assets
Available-for-sale securities	8,370	7,349
Trading securities	3	6
Fair Value | Recurring | CLO | Related Party
Assets
Available-for-sale securities	1,344	936
Trading securities	52	74
Fair Value | Recurring | ABS
Assets
Available-for-sale securities	4,200	5,118
Trading securities	119	108
Fair Value | Recurring | ABS | Related Party
Assets
Available-for-sale securities	2,729	2,849
Trading securities	1,345	711
Fair Value | Recurring | CMBS
Assets
Available-for-sale securities	2,239	2,400
Trading securities	52	51
Fair Value | Recurring | RMBS
Assets
Available-for-sale securities	6,710	7,375
Trading securities	$ 237	$ 303