Investments - Net Investment Income (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Components of net investment income
Gross investment income	$ 23,059	$ 20,927	$ 46,164	$ 42,663
Investment expenses	(1,316)	(1,061)	(2,633)	(2,164)
Net investment income	21,743	19,866	43,531	40,499
Fixed maturities
Components of net investment income
Gross investment income	23,012	20,569	46,036	41,183
Short-term investments
Components of net investment income
Gross investment income	$ 47	$ 358	$ 128	$ 1,480

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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Amount of expenses related to the generation of investment income.

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Amount, after 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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