Investments - Net Investment Income (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net investment income
Investment income, before expense	$ 399	$ 410	$ 1,180	$ 1,285
Investment expense	(26)	(25)	(79)	(74)
Net investment income	373	385	1,101	1,211
Fixed income securities
Net investment income
Investment income, before expense	235	247	721	745
Mortgage loans
Net investment income
Investment income, before expense	48	44	140	141
Equity securities
Net investment income
Investment income, before expense	6	7	26	30
Limited partnership interests
Net investment income
Investment income, before expense	69	74	174	262
Short-term investments
Net investment income
Investment income, before expense	8	7	24	16
Policy loans
Net investment income
Investment income, before expense	9	8	25	23
Other
Net investment income
Investment income, before expense	$ 24	$ 23	$ 70	$ 68

Represents the total of interest and dividend income, including any amortization and accretion (as applicable) of discounts and premiums, earned from (1) loans and leases whether held-for-sale or held-in-portfolio; (2) investment securities; (3) federal funds sold; (4) securities purchased under agreements to resell; (5) investments in banker's acceptances, commercial paper, or certificates of deposit; (6) dividend income; or (7) other investments not otherwise specified herein.

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