Investments (Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	$ 129,430	$ 129,022
Less: investment expenses	(6,393)	(3,953)
Net investment income	123,037	125,069
Equity securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	67	73
Commercial mortgage and other loans
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	13,182	11,732
Policy loans
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	127	59
Short-term investments and cash equivalents
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	25,452	13,740
Other invested assets
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	(12,713)	8,842
Available-for-sale \| Fixed maturities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	100,734	92,211
Trading \| Fixed maturities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	$ 2,581	$ 2,365

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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