Investments - Net Investment Income (Details) - Consolidated Entity Excluding Variable Interest Entities (VIE) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Net Investment Income [Line Items]
Investment revenue	$ 1,256	$ 1,046	$ 2,417	$ 1,985
Investment expenses	(95)	(88)	(190)	(172)
Net investment income	1,161	958	2,227	1,813
AFS securities
Net Investment Income [Line Items]
Investment revenue	763	719	1,516	1,387
Trading securities
Net Investment Income [Line Items]
Investment revenue	49	54	91	98
Equity securities
Net Investment Income [Line Items]
Investment revenue	4	2	7	4
Mortgage loans
Net Investment Income [Line Items]
Investment revenue	159	104	310	195
Investment funds
Net Investment Income [Line Items]
Investment revenue	102	58	112	123
Funds withheld at interest
Net Investment Income [Line Items]
Investment revenue	134	86	297	132
Other
Net Investment Income [Line Items]
Investment revenue	$ 45	$ 23	$ 84	$ 46

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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