Fair Value (Recurring Fair Value Measurements) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	$ 81,299	$ 69,977
Available-for-sale Securities, Equity Securities	133	147
Short-term investments, principally at estimated fair value	1,885	1,482
Derivative assets	3,852	3,222
Net embedded derivatives within asset host contracts	283	217
Separate account assets	103,986	99,668
Liabilities [Abstract]
Derivative liabilities	9,608	7,119
Net embedded derivatives within liability host contracts	7,584	4,582
Recurring
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	81,299	69,977
Available-for-sale Securities, Equity Securities	133	147
Short-term investments, principally at estimated fair value	1,885	1,482
Derivative assets	3,569	3,005
Net embedded derivatives within asset host contracts	283	217
Separate account assets	103,986	99,668
Total assets	191,155	174,496
Liabilities [Abstract]
Derivative liabilities	2,024	2,537
Net embedded derivatives within liability host contracts	7,584	4,582
Total liabilities	9,608	7,119
Recurring | Interest rate
Assets [Abstract]
Derivative assets	2,094	1,778
Liabilities [Abstract]
Derivative liabilities	200	330
Recurring | Foreign currency exchange rate
Assets [Abstract]
Derivative assets	207	270
Liabilities [Abstract]
Derivative liabilities	144	43
Recurring | Credit
Assets [Abstract]
Derivative assets	41	36
Recurring | Equity market
Assets [Abstract]
Derivative assets	1,227	921
Liabilities [Abstract]
Derivative liabilities	1,680	2,164
Recurring | U.S. Corporate
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	37,276	30,591
Recurring | Foreign Corporate
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	11,375	9,686
Recurring | RMBS
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	8,219	9,030
Recurring | U.S. Government and Agency
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	8,464	7,244
Recurring | CMBS
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	6,697	5,714
Recurring | State and Political Subdivision
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	4,555	4,011
Recurring | ABS
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	2,881	1,950
Recurring | Foreign Government
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	1,832	1,751
Recurring | Level 1
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	2,108	1,542
Available-for-sale Securities, Equity Securities	31	14
Short-term investments, principally at estimated fair value	1,669	1,004
Derivative assets	0	0
Net embedded derivatives within asset host contracts	0	0
Separate account assets	86	180
Total assets	3,894	2,740
Liabilities [Abstract]
Derivative liabilities	0	0
Net embedded derivatives within liability host contracts	0	0
Total liabilities	0	0
Recurring | Level 1 | Interest rate
Assets [Abstract]
Derivative assets	0	0
Liabilities [Abstract]
Derivative liabilities	0	0
Recurring | Level 1 | Foreign currency exchange rate
Assets [Abstract]
Derivative assets	0	0
Liabilities [Abstract]
Derivative liabilities	0	0
Recurring | Level 1 | Credit
Assets [Abstract]
Derivative assets	0	0
Recurring | Level 1 | Equity market
Assets [Abstract]
Derivative assets	0	0
Liabilities [Abstract]
Derivative liabilities	0	0
Recurring | Level 1 | U.S. Corporate
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	0	0
Recurring | Level 1 | Foreign Corporate
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	0	0
Recurring | Level 1 | RMBS
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	0	0
Recurring | Level 1 | U.S. Government and Agency
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	2,108	1,542
Recurring | Level 1 | CMBS
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	0	0
Recurring | Level 1 | State and Political Subdivision
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	0	0
Recurring | Level 1 | ABS
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	0	0
Recurring | Level 1 | Foreign Government
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	0	0
Recurring | Level 2
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	78,440	67,788
Available-for-sale Securities, Equity Securities	99	125
Short-term investments, principally at estimated fair value	216	473
Derivative assets	3,540	2,918
Net embedded derivatives within asset host contracts	0	0
Separate account assets	103,897	99,485
Total assets	186,192	170,789
Liabilities [Abstract]
Derivative liabilities	1,997	2,466
Net embedded derivatives within liability host contracts	0	0
Total liabilities	1,997	2,466
Recurring | Level 2 | Interest rate
Assets [Abstract]
Derivative assets	2,094	1,778
Liabilities [Abstract]
Derivative liabilities	200	330
Recurring | Level 2 | Foreign currency exchange rate
Assets [Abstract]
Derivative assets	206	265
Liabilities [Abstract]
Derivative liabilities	137	43
Recurring | Level 2 | Credit
Assets [Abstract]
Derivative assets	27	25
Recurring | Level 2 | Equity market
Assets [Abstract]
Derivative assets	1,213	850
Liabilities [Abstract]
Derivative liabilities	1,660	2,093
Recurring | Level 2 | U.S. Corporate
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	36,789	30,266
Recurring | Level 2 | Foreign Corporate
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	11,178	9,554
Recurring | Level 2 | RMBS
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	8,197	8,986
Recurring | Level 2 | U.S. Government and Agency
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	6,356	5,702
Recurring | Level 2 | CMBS
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	6,692	5,714
Recurring | Level 2 | State and Political Subdivision
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	4,555	3,938
Recurring | Level 2 | ABS
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	2,841	1,877
Recurring | Level 2 | Foreign Government
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	1,832	1,751
Recurring | Level 3
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	751	647
Available-for-sale Securities, Equity Securities	3	8
Short-term investments, principally at estimated fair value	0	5
Derivative assets	29	87
Net embedded derivatives within asset host contracts	283	217
Separate account assets	3	3
Total assets	1,069	967
Liabilities [Abstract]
Derivative liabilities	27	71
Net embedded derivatives within liability host contracts	7,584	4,582
Total liabilities	7,611	4,653
Recurring | Level 3 | Interest rate
Assets [Abstract]
Derivative assets	0	0
Liabilities [Abstract]
Derivative liabilities	0	0
Recurring | Level 3 | Foreign currency exchange rate
Assets [Abstract]
Derivative assets	1	5
Liabilities [Abstract]
Derivative liabilities	7	0
Recurring | Level 3 | Credit
Assets [Abstract]
Derivative assets	14	11
Recurring | Level 3 | Equity market
Assets [Abstract]
Derivative assets	14	71
Liabilities [Abstract]
Derivative liabilities	20	71
Recurring | Level 3 | U.S. Corporate
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	487	325
Recurring | Level 3 | Foreign Corporate
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	197	132
Recurring | Level 3 | RMBS
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	22	44
Recurring | Level 3 | U.S. Government and Agency
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	0	0
Recurring | Level 3 | CMBS
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	5	0
Recurring | Level 3 | State and Political Subdivision
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	0	73
Recurring | Level 3 | ABS
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	40	73
Recurring | Level 3 | Foreign Government
Assets [Abstract]
Fixed maturity securities available-for-sale, at estimated fair value (amortized cost: $69,483 and $63,083, respectively; allowance for credit losses of $2 and $0, respectively)	$ 0	$ 0