Investments (Commercial Mortgage and Other Loans) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 1,685,584	$ 1,474,185
Commercial mortgage loans, Percentage	100.00%	100.00%
Allowance for credit losses	$ (7,633)	$ (2,663)
Total net other loans	0	0
Allowance for credit losses, other loans	0	0
Total commercial mortgage and other loans	1,677,951	1,471,522
Commercial Mortgage and Agricultural Loans
Commercial Mortgage and Other Loans [Line Items]
Total net other loans	1,677,951	1,471,522
Other Collateralized Loans
Commercial Mortgage and Other Loans [Line Items]
Other loans	0	0
Apartments and multi-family
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 371,216	$ 272,150
Commercial mortgage loans, Percentage	22.00%	18.50%
Hospitality
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 16,745	$ 16,819
Commercial mortgage loans, Percentage	1.00%	1.10%
Industrial
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 520,721	$ 464,528
Commercial mortgage loans, Percentage	30.90%	31.50%
Office
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 365,535	$ 372,823
Commercial mortgage loans, Percentage	21.70%	25.30%
Other
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 187,116	$ 156,768
Commercial mortgage loans, Percentage	11.10%	10.60%
Retail
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 130,462	$ 131,051
Commercial mortgage loans, Percentage	7.70%	8.90%
Commercial Mortgage Loans
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 1,591,795	$ 1,414,139
Commercial mortgage loans, Percentage	94.40%	95.90%
Agricultural property loans
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 93,789	$ 60,046
Commercial mortgage loans, Percentage	5.60%	4.10%

Commercial mortgage loans, Percentage

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Commercial mortgage and agricultural property loans by property type

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Commercial mortgage and other loans

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Other loans

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The reserve to cover probable credit losses related to specifically identified fixed maturity real estate loans as well as probable credit losses inherent in the remainder of that loan portfolio.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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