Investments (Commercial Mortgage and Other Loans) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 6,155,050	$ 4,948,943
Commercial mortgage loans, Percentage	100.00%	100.00%
Allowance for Credit Losses	$ (37,689)	$ (20,263)
Commercial Mortgage Loans	6,122,721	4,928,680
Total net Commercial Mortgage and Other Loans	6,122,721	4,928,680
Other loans	5,360	0
Commercial Mortgage and Agricultural Loans
Commercial Mortgage and Other Loans [Line Items]
Commercial Mortgage Loans	6,117,361	4,928,680
Total net Commercial Mortgage and Other Loans	6,117,361	4,928,680
Collateralized Loan Obligations
Commercial Mortgage and Other Loans [Line Items]
Other loans	5,360	0
Total Net Commercial Mortgage and Other Loans
Commercial Mortgage and Other Loans [Line Items]
Commercial Mortgage Loans	6,122,721	4,928,680
Total net Commercial Mortgage and Other Loans	6,122,721	4,928,680
Apartments and multi-family
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 1,578,785	$ 1,289,026
Commercial mortgage loans, Percentage	25.70%	26.00%
Hospitality
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 102,952	$ 104,177
Commercial mortgage loans, Percentage	1.70%	2.10%
Industrial
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 2,486,230	$ 1,766,247
Commercial mortgage loans, Percentage	40.40%	35.80%
Office
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 604,611	$ 590,897
Commercial mortgage loans, Percentage	9.80%	11.90%
Other
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 456,720	$ 380,121
Commercial mortgage loans, Percentage	7.40%	7.70%
Retail
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 363,706	$ 351,457
Commercial mortgage loans, Percentage	5.90%	7.10%
Commercial mortgage loans
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 5,593,004	$ 4,481,925
Commercial mortgage loans, Percentage	90.90%	90.60%
Agricultural property loans
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 562,046	$ 467,018
Commercial mortgage loans, Percentage	9.10%	9.40%