Investments - Net Investment Income (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Net investment income
Investment income, before expense	$ 338	$ 431
Investment expense	(27)	(24)
Net investment income	311	407
Fixed income securities
Net investment income
Investment income, before expense	245	251
Mortgage loans
Net investment income
Investment income, before expense	46	44
Equity securities
Net investment income
Investment income, before expense	6	7
Limited partnership interests
Net investment income
Investment income, before expense	3	96
Short-term investments
Net investment income
Investment income, before expense	8	4
Policy loans
Net investment income
Investment income, before expense	8	7
Other
Net investment income
Investment income, before expense	$ 22	$ 22

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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