Investments (Net Investment Income) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net Investment Income [Line Items]
Less: Investment expenses	$ 1,285	$ 1,122	$ 972
Net Investment Income	16,166	17,363	16,790
Securities Investment
Net Investment Income [Line Items]
Gross Investment Income, Operating	18,134	17,185	16,812
Net Investment Income	16,849	16,063	15,840
Fixed Maturity Securities
Net Investment Income [Line Items]
Gross Investment Income, Operating	11,946	11,497	11,721
Equity securities
Net Investment Income [Line Items]
Gross Investment Income, Operating	64	129	121
FVO Securities (1)
Net Investment Income [Line Items]
Gross Investment Income, Operating	51	68	37
Mortgage Loans
Net Investment Income [Line Items]
Gross Investment Income, Operating	3,340	3,082	2,858
Policy loans
Net Investment Income [Line Items]
Gross Investment Income, Operating	506	517	511
Real estate and real estate joint ventures
Net Investment Income [Line Items]
Gross Investment Income, Operating	694	646	652
Other limited partnership interests
Net Investment Income [Line Items]
Gross Investment Income, Operating	731	798	478
Cash, cash equivalents and short-term investments
Net Investment Income [Line Items]
Gross Investment Income, Operating	387	228	153
Operating joint ventures
Net Investment Income [Line Items]
Gross Investment Income, Operating	51	28	33
Other
Net Investment Income [Line Items]
Gross Investment Income, Operating	364	192	248
FVO contractholder-directed unit-linked investments
Net Investment Income [Line Items]
Net Investment Income	(683)	1,300	950
Trading Securities, Change in Unrealized Holding Gain (Loss)	$ (771)	$ 662	$ 427

Amount, before investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

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