Investments (Fixed Maturity Securities by Sector) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, amortized cost	$ 66,496	$ 64,079
Fixed maturity securities, allowance for credit losses	5	0
Fixed maturity securities, gross unrealized gains	10,766	7,136
Fixed maturity securities, gross unrealized losses	461	179
Fixed maturity securities, estimated fair value	76,796	71,036
U.S. Corporate
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, amortized cost	30,157	28,375
Fixed maturity securities, allowance for credit losses	2	0
Fixed maturity securities, gross unrealized gains	4,314	2,852
Fixed maturity securities, gross unrealized losses	204	67
Fixed maturity securities, estimated fair value	34,265	31,160
Foreign Corporate
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, amortized cost	9,580	9,177
Fixed maturity securities, allowance for credit losses	2	0
Fixed maturity securities, gross unrealized gains	881	741
Fixed maturity securities, gross unrealized losses	168	74
Fixed maturity securities, estimated fair value	10,291	9,844
RMBS
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, amortized cost	7,980	8,692
Fixed maturity securities, allowance for credit losses	1	0
Fixed maturity securities, gross unrealized gains	617	438
Fixed maturity securities, gross unrealized losses	12	12
Fixed maturity securities, estimated fair value	8,584	9,118
U.S. Government and Agency
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, amortized cost	5,673	5,529
Fixed maturity securities, allowance for credit losses	0	0
Fixed maturity securities, gross unrealized gains	3,252	1,869
Fixed maturity securities, gross unrealized losses	0	2
Fixed maturity securities, estimated fair value	8,925	7,396
CMBS
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, amortized cost	5,805	5,500
Fixed maturity securities, allowance for credit losses	0	0
Fixed maturity securities, gross unrealized gains	473	264
Fixed maturity securities, gross unrealized losses	23	9
Fixed maturity securities, estimated fair value	6,255	5,755
State and Political Subdivision
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, amortized cost	3,329	3,358
Fixed maturity securities, allowance for credit losses	0	0
Fixed maturity securities, gross unrealized gains	904	701
Fixed maturity securities, gross unrealized losses	1	2
Fixed maturity securities, estimated fair value	4,232	4,057
ABS
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, amortized cost	2,469	1,945
Fixed maturity securities, allowance for credit losses	0	0
Fixed maturity securities, gross unrealized gains	40	21
Fixed maturity securities, gross unrealized losses	46	11
Fixed maturity securities, estimated fair value	2,463	1,955
Foreign Government
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, amortized cost	1,503	1,503
Fixed maturity securities, allowance for credit losses	0	0
Fixed maturity securities, gross unrealized gains	285	250
Fixed maturity securities, gross unrealized losses	7	2
Fixed maturity securities, estimated fair value	$ 1,781	$ 1,751

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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