Investments - Net Investment Income (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Net investment income
Investment income, before expense	$ 443	$ 444	$ 781	$ 875
Investment expense	(26)	(25)	(53)	(49)
Net investment income	417	419	728	826
Fixed income securities
Net investment income
Investment income, before expense	241	247	486	498
Mortgage loans
Net investment income
Investment income, before expense	46	53	92	97
Equity securities
Net investment income
Investment income, before expense	14	16	20	23
Limited partnership interests
Net investment income
Investment income, before expense	102	92	105	188
Short-term investments
Net investment income
Investment income, before expense	8	5	16	9
Policy loans
Net investment income
Investment income, before expense	8	8	16	15
Other
Net investment income
Investment income, before expense	$ 24	$ 23	$ 46	$ 45

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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