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Amount, after accumulated amortization, of debt discount.

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Amount, after accumulated amortization, of debt premium.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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Amount of allowance for credit losses related to recorded investment.

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Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

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Amount before accretion (amortization) of purchase discount (premium) of interest income on nonoperating securities.

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Amount after accretion (amortization) of discount (premium), and investment expense, of interest income and dividend income on nonoperating securities.

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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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Amount, after allowance for credit loss, of financing receivable. Excludes financing receivable covered under loss sharing agreement.

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The amount by which the fair value of an investment in debt and equity securities categorized as Available-for-sale is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Fair value of financial instrument held by the entity for its own account (proprietary securities) for trading or investment purposes that are carried at fair value and pledged to counterparties as collateral for financing transactions.

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Investments - Narrative (Details)	12 Months Ended
Investments - Narrative (Details)	Dec. 31, 2019 USD ($) issuer loan	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) loan	Mar. 31, 2018 USD ($)
Debt Securities, Available-for-sale [Line Items]
Number of available-for-sale securities held in an unrealized loss position \| issuer	112
Total fair value of unrealized loss position securities	$ 265,969,000	$ 852,854,000
Gross unrealized losses	2,598,000	21,267,000
Impairment loss			$ 1,500,000
Number of impaired loans \| loan			5
Carrying value of impaired loans	6,900,000		$ 5,100,000
Unpaid principal on impaired loans	14,300,000		8,400,000
Allowance for credit losses	7,200,000		3,200,000
Carrying value of loan	260,864,000	260,972,000
Net Investment Income	75,652,000	61,256,000	61,119,000
Fixed maturity securities, available-for-sale	1,433,626,000	1,184,202,000
Investment as collateral for outstanding letters of credit	464,500,000
Investments on deposit with state insurance departments	36,600,000	25,500,000
Investment Income	6,254,000	5,165,000	14,079,000
Bank Holding Company
Debt Securities, Available-for-sale [Line Items]
Interest income	343,000	343,000	343,000
Available-for-sale fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, available-for-sale	$ 1,433,626,000	1,184,202,000
Puerto Rico loan
Debt Securities, Available-for-sale [Line Items]
Unpaid principal on impaired loans			807,000
Carrying value of loan			0
Realized gain on repayment				$ 807,000
Impaired bank loans
Debt Securities, Available-for-sale [Line Items]
Number of impaired loans \| loan	7
Number Of Issuers With Impaired Loans \| issuer	6
Average recorded investment in impaired bank loans	$ 3,500,000	2,600,000	5,800,000
Net Investment Income	293,000	125,000	300,000
Net realized gain (loss) on changes in fair value of impaired bank loans	$ (8,900,000)	(858,000)	(2,400,000)
Loans from issuer experiencing liquidity concerns
Debt Securities, Available-for-sale [Line Items]
Number of impaired loans \| loan	2
Number Of Issuers With Impaired Loans \| issuer	1
Allowance for credit losses	$ 5,100,000
Bank loan participations
Debt Securities, Available-for-sale [Line Items]
Unamortized discount	2,400,000	1,800,000
Unamortized premium	$ 4,000	17,000
Standard & Poor's, BBB- Rating \| Available-for-sale fixed maturity securities
Debt Securities, Available-for-sale [Line Items]
Percentage of available for sale securities	99.60%
Renewable Energy Bridge Financing Notes
Debt Securities, Available-for-sale [Line Items]
Interest income	$ 1,300,000	1,300,000	526,000
Investment Income	1,313,000	1,282,000	526,000
Bank Holding Company
Debt Securities, Available-for-sale [Line Items]
Fixed maturity securities, available-for-sale	$ 3,200,000	$ 4,200,000
Bank Holding Company \| Bank Holding Company
Debt Securities, Available-for-sale [Line Items]
Gross realized gains			$ 409,000