Investments - Commercial Mortgage Loan Participations (Details) - Commercial mortgage participations $ in Thousands	Mar. 31, 2020 USD ($) loan	Dec. 31, 2019 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 162,176	$ 137,692
Carrying value, gross, percent	100.00%	100.00%
Allowance for credit losses	$ (335)	$ 0
Allowance for credit losses, percent	0.00%	0.00%
Carrying value, net of valuation allowance	$ 161,841	$ 137,692
Carrying value, net, percent	100.00%	100.00%
Number of loans \| loan	27
South Atlantic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 51,539	$ 50,867
Carrying value, gross, percent	32.00%	37.00%
Pacific
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 55,909	$ 36,546
Carrying value, gross, percent	35.00%	27.00%
Middle Atlantic
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 28,073	$ 25,328
Carrying value, gross, percent	17.00%	18.00%
East North Central
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 10,579	$ 10,568
Carrying value, gross, percent	6.00%	8.00%
West South Central
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 8,368	$ 8,072
Carrying value, gross, percent	5.00%	6.00%
East South Central
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 4,684	$ 4,676
Carrying value, gross, percent	3.00%	3.00%
West North Central
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 1,386	$ 0
Carrying value, gross, percent	1.00%	0.00%
New England
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 1,638	$ 1,635
Carrying value, gross, percent	1.00%	1.00%
Office
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 42,670	$ 42,350
Carrying value, gross, percent	26.00%	31.00%
Mixed use
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 42,010	$ 27,501
Carrying value, gross, percent	26.00%	20.00%
Hospitality
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 22,602	$ 22,324
Carrying value, gross, percent	14.00%	16.00%
Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 22,422	$ 17,612
Carrying value, gross, percent	14.00%	13.00%
Retail
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 18,605	$ 17,318
Carrying value, gross, percent	11.00%	12.00%
Multi-family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, gross	$ 13,867	$ 10,587
Carrying value, gross, percent	9.00%	8.00%

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

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Amount, before allowance for credit loss, of financing receivable.

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