Fair Value - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Assets
Available-for-sale securities	$ 92,429	$ 89,373
Mortgage loans	17,385	15,938
Derivative assets	3,677	3,523
Restricted cash	546	738
Reinsurance recoverable (portion at fair value: 2021 – $1,880 and 2020 – $2,100)	4,690	4,848
Liabilities
Interest sensitive contract liabilities	146,247	144,566
Future policy benefits	31,767	29,258
Derivative liabilities	288	298
Funds withheld liability (portion at fair value: 2021 – $34 and 2020 – $59)	422	452
Related Party
Assets
Available-for-sale securities	6,905	6,520
Trading securities, at fair value	1,710	1,529
Equity securities, at fair value	114	72
Mortgage loans	714	674
Investment funds	2,060	2,119
Funds withheld at interest	12,572	13,030
Other investments	469	469
Liabilities
Interest sensitive contract liabilities	13,830	14,150
Future policy benefits	1,665	1,610
Corporate | Related Party
Assets
Available-for-sale securities	221	215
CLO | Related Party
Assets
Available-for-sale securities	1,869	1,520
ABS | Related Party
Assets
Available-for-sale securities	4,815	4,785
Level 3
Assets
Available-for-sale securities	5,982	5,858
Recurring
Assets
Investment funds		230
Recurring | Level 1
Assets
Cash and cash equivalents	6,427	7,704
Restricted cash	546	738
Reinsurance recoverable (portion at fair value: 2021 – $1,880 and 2020 – $2,100)	0	0
Total assets measured at fair value	7,445	9,038
Liabilities
Derivative liabilities	0	2
Total liabilities measured at fair value	0	2
Recurring | Level 1 | Related Party
Assets
Available-for-sale securities	0	0
Trading securities, at fair value	0	0
Equity securities, at fair value	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
Liabilities
Interest sensitive contract liabilities	0	0
Funds withheld liability (portion at fair value: 2021 – $34 and 2020 – $59)	0	0
Recurring | Level 1 | Embedded derivatives | Related Party
Assets
Funds withheld at interest	0	0
Recurring | Level 1 | Corporate | Related Party
Assets
Available-for-sale securities	0	0
Recurring | Level 1 | CLO | Related Party
Assets
Available-for-sale securities	0	0
Trading securities, at fair value	0	0
Recurring | Level 1 | ABS | Related Party
Assets
Available-for-sale securities	0	0
Trading securities, at fair value	0	0
Recurring | Level 2
Assets
Cash and cash equivalents	0	0
Restricted cash	0	0
Reinsurance recoverable (portion at fair value: 2021 – $1,880 and 2020 – $2,100)	0	0
Total assets measured at fair value	91,529	88,786
Liabilities
Derivative liabilities	283	292
Total liabilities measured at fair value	317	351
Recurring | Level 2 | Related Party
Assets
Available-for-sale securities	2,573	2,216
Trading securities, at fair value	25	4
Equity securities, at fair value	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
Liabilities
Interest sensitive contract liabilities	0	0
Funds withheld liability (portion at fair value: 2021 – $34 and 2020 – $59)	34	59
Recurring | Level 2 | Embedded derivatives | Related Party
Assets
Funds withheld at interest	0	0
Recurring | Level 2 | Corporate | Related Party
Assets
Available-for-sale securities	20	20
Recurring | Level 2 | CLO | Related Party
Assets
Available-for-sale securities	1,869	1,520
Trading securities, at fair value	25	4
Recurring | Level 2 | ABS | Related Party
Assets
Available-for-sale securities	684	676
Trading securities, at fair value	0	0
Recurring | Level 3
Assets
Cash and cash equivalents	0	0
Restricted cash	0	0
Reinsurance recoverable (portion at fair value: 2021 – $1,880 and 2020 – $2,100)	1,880	2,100
Total assets measured at fair value	13,707	14,840
Liabilities
Derivative liabilities	5	4
Total liabilities measured at fair value	15,840	16,561
Recurring | Level 3 | Related Party
Assets
Available-for-sale securities	4,332	4,304
Trading securities, at fair value	1,685	1,525
Equity securities, at fair value	114	72
Investment funds	1,970	2,033
Recurring | Level 3 | Universal life
Liabilities
Interest sensitive contract liabilities	1,108	1,308
Recurring | Level 3 | AmerUs Closed Block
Liabilities
Future policy benefits	1,497	1,600
Recurring | Level 3 | ILICO Closed Block and life benefits
Liabilities
Future policy benefits	757	776
Recurring | Level 3 | Embedded derivatives
Liabilities
Interest sensitive contract liabilities	12,473	12,873
Funds withheld liability (portion at fair value: 2021 – $34 and 2020 – $59)	0	0
Recurring | Level 3 | Embedded derivatives | Related Party
Assets
Funds withheld at interest	580	862
Recurring | Level 3 | Corporate | Related Party
Assets
Available-for-sale securities	201	195
Recurring | Level 3 | CLO | Related Party
Assets
Available-for-sale securities	0	0
Trading securities, at fair value	44	50
Recurring | Level 3 | ABS | Related Party
Assets
Available-for-sale securities	4,131	4,109
Trading securities, at fair value	1,641	1,475
Recurring | NAV
Assets
Total assets measured at fair value	238
Recurring | NAV | Related Party
Assets
Investment funds	90	86
Fair Value
Assets
Total assets measured at fair value	82,249	80,487
Liabilities
Interest sensitive contract liabilities	99,298	98,945
Funds withheld liability (portion at fair value: 2021 – $34 and 2020 – $59)	388	393
Fair Value | Related Party
Assets
Mortgage loans	734	694
Investment funds	3,839	3,165
Funds withheld at interest	11,992	12,168
Other investments	492	499
Fair Value | Level 1
Assets
Total assets measured at fair value	0	0
Liabilities
Interest sensitive contract liabilities	0	0
Funds withheld liability (portion at fair value: 2021 – $34 and 2020 – $59)	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
Total assets measured at fair value	356	369
Liabilities
Interest sensitive contract liabilities	0	0
Funds withheld liability (portion at fair value: 2021 – $34 and 2020 – $59)	388	393
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
Total assets measured at fair value	77,407	76,311
Liabilities
Interest sensitive contract liabilities	99,298	98,945
Funds withheld liability (portion at fair value: 2021 – $34 and 2020 – $59)	0	0
Fair Value | Level 3 | Related Party
Assets
Mortgage loans	734	694
Investment funds	0	0
Funds withheld at interest	11,992	12,168
Other investments	492	499
Fair Value | NAV
Assets
Total assets measured at fair value	4,486	3,807
Fair Value | NAV | Related Party
Assets
Investment funds	3,839	3,165
Fair Value | Recurring
Assets
Cash and cash equivalents	6,427	7,704
Restricted cash	546	738
Reinsurance recoverable (portion at fair value: 2021 – $1,880 and 2020 – $2,100)	1,880	2,100
Total assets measured at fair value	112,919	112,894
Liabilities
Interest sensitive contract liabilities	13,581	14,181
Future policy benefits	2,254	2,376
Derivative liabilities	288	298
Funds withheld liability (portion at fair value: 2021 – $34 and 2020 – $59)	34	59
Total liabilities measured at fair value	16,157	16,914
Fair Value | Recurring | Related Party
Assets
Available-for-sale securities	6,905	6,520
Trading securities, at fair value	1,710	1,529
Equity securities, at fair value	114	72
Investment funds	2,060	2,119
Funds withheld at interest	580	862
Fair Value | Recurring | Universal life
Liabilities
Interest sensitive contract liabilities	1,108	1,308
Fair Value | Recurring | AmerUs Closed Block
Liabilities
Future policy benefits	1,497	1,600
Fair Value | Recurring | ILICO Closed Block and life benefits
Liabilities
Future policy benefits	757	776
Fair Value | Recurring | Embedded derivatives
Liabilities
Interest sensitive contract liabilities	12,473	12,873
Funds withheld liability (portion at fair value: 2021 – $34 and 2020 – $59)	34	59
Fair Value | Recurring | Embedded derivatives | Related Party
Assets
Funds withheld at interest	580	862
Fair Value | Recurring | Corporate | Related Party
Assets
Available-for-sale securities	221	215
Fair Value | Recurring | CLO | Related Party
Assets
Available-for-sale securities	1,869	1,520
Trading securities, at fair value	69	54
Fair Value | Recurring | ABS | Related Party
Assets
Available-for-sale securities	4,815	4,785
Trading securities, at fair value	1,641	1,475
Investments, excluding investments in Related Party
Assets
Available-for-sale securities	85,524	82,853
Trading securities, at fair value	1,979	2,093
Mortgage loans	16,671	15,264
Investment funds	319	161
Funds withheld at interest	46,024	48,612
Derivative assets	3,677	3,523
Short-term investments	125	222
Other investments	1,722	572
Investments, excluding investments in Related Party | Related Party
Assets
Available-for-sale securities	6,905	6,520
Investments, excluding investments in Related Party | U.S. government and agencies
Assets
Available-for-sale securities	351	351
Investments, excluding investments in Related Party | U.S. state, municipal and political subdivisions
Assets
Available-for-sale securities	1,006	1,033
Investments, excluding investments in Related Party | Foreign governments
Assets
Available-for-sale securities	382	368
Investments, excluding investments in Related Party | Corporate
Assets
Available-for-sale securities	58,848	58,180
Investments, excluding investments in Related Party | CLO
Assets
Available-for-sale securities	11,272	9,569
Investments, excluding investments in Related Party | ABS
Assets
Available-for-sale securities	4,832	4,270
Investments, excluding investments in Related Party | CMBS
Assets
Available-for-sale securities	2,206	2,169
Investments, excluding investments in Related Party | RMBS
Assets
Available-for-sale securities	6,627	6,913
Investments, excluding investments in Related Party | Recurring | Level 1
Assets
Available-for-sale securities	342	332
Trading securities, at fair value	3	3
Equity securities, at fair value	36	57
Mortgage loans	0	0
Investment funds	0	0
Derivative assets	40	58
Short-term investments	51	146
Other investments	0	0
Investments, excluding investments in Related Party | Recurring | Level 1 | Embedded derivatives
Assets
Funds withheld at interest	0	0
Investments, excluding investments in Related Party | Recurring | Level 1 | U.S. government and agencies
Assets
Available-for-sale securities	342	332
Trading securities, at fair value	3	3
Investments, excluding investments in Related Party | Recurring | Level 1 | U.S. state, municipal and political subdivisions
Assets
Available-for-sale securities	0	0
Trading securities, at fair value	0	0
Investments, excluding investments in Related Party | Recurring | Level 1 | Foreign governments
Assets
Available-for-sale securities	0	0
Investments, excluding investments in Related Party | Recurring | Level 1 | Corporate
Assets
Available-for-sale securities	0	0
Trading securities, at fair value	0	0
Investments, excluding investments in Related Party | Recurring | Level 1 | CLO
Assets
Available-for-sale securities	0	0
Trading securities, at fair value		0
Investments, excluding investments in Related Party | Recurring | Level 1 | ABS
Assets
Available-for-sale securities	0	0
Trading securities, at fair value	0	0
Investments, excluding investments in Related Party | Recurring | Level 1 | CMBS
Assets
Available-for-sale securities	0	0
Trading securities, at fair value	0	0
Investments, excluding investments in Related Party | Recurring | Level 1 | RMBS
Assets
Available-for-sale securities	0	0
Trading securities, at fair value	0	0
Investments, excluding investments in Related Party | Recurring | Level 2
Assets
Available-for-sale securities	82,969	80,656
Trading securities, at fair value	1,882	2,004
Equity securities, at fair value	272	262
Mortgage loans	0	0
Investment funds	0	0
Derivative assets	3,637	3,465
Short-term investments	66	74
Other investments	105	105
Investments, excluding investments in Related Party | Recurring | Level 2 | Embedded derivatives
Assets
Funds withheld at interest	0	0
Investments, excluding investments in Related Party | Recurring | Level 2 | U.S. government and agencies
Assets
Available-for-sale securities	9	19
Trading securities, at fair value	3	3
Investments, excluding investments in Related Party | Recurring | Level 2 | U.S. state, municipal and political subdivisions
Assets
Available-for-sale securities	1,006	999
Trading securities, at fair value	100	106
Investments, excluding investments in Related Party | Recurring | Level 2 | Foreign governments
Assets
Available-for-sale securities	380	366
Investments, excluding investments in Related Party | Recurring | Level 2 | Corporate
Assets
Available-for-sale securities	58,066	57,402
Trading securities, at fair value	1,486	1,577
Investments, excluding investments in Related Party | Recurring | Level 2 | CLO
Assets
Available-for-sale securities	11,098	9,361
Trading securities, at fair value		0
Investments, excluding investments in Related Party | Recurring | Level 2 | ABS
Assets
Available-for-sale securities	3,625	3,470
Trading securities, at fair value	97	93
Investments, excluding investments in Related Party | Recurring | Level 2 | CMBS
Assets
Available-for-sale securities	2,158	2,126
Trading securities, at fair value	57	52
Investments, excluding investments in Related Party | Recurring | Level 2 | RMBS
Assets
Available-for-sale securities	6,627	6,913
Trading securities, at fair value	139	173
Investments, excluding investments in Related Party | Recurring | Level 3
Assets
Available-for-sale securities	2,213	1,865
Trading securities, at fair value	94	86
Equity securities, at fair value	14	11
Mortgage loans	18	19
Investment funds	171	17
Derivative assets	0	0
Short-term investments	0	2
Other investments	0	0
Investments, excluding investments in Related Party | Recurring | Level 3 | Embedded derivatives
Assets
Funds withheld at interest	636	1,944
Investments, excluding investments in Related Party | Recurring | Level 3 | U.S. government and agencies
Assets
Available-for-sale securities	0	0
Trading securities, at fair value	0	0
Investments, excluding investments in Related Party | Recurring | Level 3 | U.S. state, municipal and political subdivisions
Assets
Available-for-sale securities	0	34
Trading securities, at fair value	0	0
Investments, excluding investments in Related Party | Recurring | Level 3 | Foreign governments
Assets
Available-for-sale securities	2	2
Investments, excluding investments in Related Party | Recurring | Level 3 | Corporate
Assets
Available-for-sale securities	782	778
Trading securities, at fair value	0	0
Investments, excluding investments in Related Party | Recurring | Level 3 | CLO
Assets
Available-for-sale securities	174	208
Trading securities, at fair value		4
Investments, excluding investments in Related Party | Recurring | Level 3 | ABS
Assets
Available-for-sale securities	1,207	800
Trading securities, at fair value	35	35
Investments, excluding investments in Related Party | Recurring | Level 3 | CMBS
Assets
Available-for-sale securities	48	43
Trading securities, at fair value	0	0
Investments, excluding investments in Related Party | Recurring | Level 3 | RMBS
Assets
Available-for-sale securities	0	0
Trading securities, at fair value	59	47
Investments, excluding investments in Related Party | Recurring | NAV
Assets
Investment funds	148	144
Investments, excluding investments in Related Party | Fair Value
Assets
Mortgage loans	17,176	15,811
Investment funds	647	642
Funds withheld at interest	45,388	46,668
Short-term investments	8
Other investments	1,617	471
Investments, excluding investments in Related Party | 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
Investments, excluding investments in Related Party | 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
Investments, excluding investments in Related Party | Fair Value | Level 3
Assets
Mortgage loans	17,176	15,811
Investment funds	0	0
Funds withheld at interest	45,388	46,668
Short-term investments	8
Other investments	1,617	471
Investments, excluding investments in Related Party | Fair Value | NAV
Assets
Investment funds	647	642
Investments, excluding investments in Related Party | Fair Value | Recurring
Assets
Available-for-sale securities	85,524	82,853
Trading securities, at fair value	1,979	2,093
Equity securities, at fair value	322	330
Mortgage loans	18	19
Investment funds	319	161
Funds withheld at interest	636	1,944
Derivative assets	3,677	3,523
Short-term investments	117	222
Other investments	105	105
Investments, excluding investments in Related Party | Fair Value | Recurring | Embedded derivatives
Assets
Funds withheld at interest	636	1,944
Investments, excluding investments in Related Party | Fair Value | Recurring | U.S. government and agencies
Assets
Available-for-sale securities	351	351
Trading securities, at fair value	6	6
Investments, excluding investments in Related Party | Fair Value | Recurring | U.S. state, municipal and political subdivisions
Assets
Available-for-sale securities	1,006	1,033
Trading securities, at fair value	100	106
Investments, excluding investments in Related Party | Fair Value | Recurring | Foreign governments
Assets
Available-for-sale securities	382	368
Investments, excluding investments in Related Party | Fair Value | Recurring | Corporate
Assets
Available-for-sale securities	58,848	58,180
Trading securities, at fair value	1,486	1,577
Investments, excluding investments in Related Party | Fair Value | Recurring | CLO
Assets
Available-for-sale securities	11,272	9,569
Trading securities, at fair value		4
Investments, excluding investments in Related Party | Fair Value | Recurring | ABS
Assets
Available-for-sale securities	4,832	4,270
Trading securities, at fair value	132	128
Investments, excluding investments in Related Party | Fair Value | Recurring | CMBS
Assets
Available-for-sale securities	2,206	2,169
Trading securities, at fair value	57	52
Investments, excluding investments in Related Party | Fair Value | Recurring | RMBS
Assets
Available-for-sale securities	6,627	6,913
Trading securities, at fair value	$ 198	$ 220