Investments (Commercial Mortgage and Other Loans) (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 6,752,746	$ 6,155,050
Commercial mortgage loans, Percentage	100.00%	100.00%
Allowance for Credit Losses	$ (41,572)	$ (37,689)
Commercial Mortgage Loans	6,718,386	6,122,721
Total net Commercial Mortgage and Other Loans	6,718,386	6,122,721
Other loans	7,212	5,360
Commercial Mortgage and Agricultural Loans
Commercial Mortgage and Other Loans [Line Items]
Commercial Mortgage Loans	6,711,174	6,117,361
Total net Commercial Mortgage and Other Loans	6,711,174	6,117,361
Other Collateralized Loans
Commercial Mortgage and Other Loans [Line Items]
Other loans	7,212	5,360
Total Net Commercial Mortgage and Other Loans
Commercial Mortgage and Other Loans [Line Items]
Commercial Mortgage Loans	6,718,386	6,122,721
Total net Commercial Mortgage and Other Loans	6,718,386	6,122,721
Apartments and multi-family
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 1,776,234	$ 1,578,785
Commercial mortgage loans, Percentage	26.30%	25.70%
Hospitality
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 99,596	$ 102,952
Commercial mortgage loans, Percentage	1.50%	1.70%
Industrial
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 2,701,470	$ 2,486,230
Commercial mortgage loans, Percentage	40.00%	40.40%
Office
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 587,978	$ 604,611
Commercial mortgage loans, Percentage	8.60%	9.80%
Other
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 666,349	$ 456,720
Commercial mortgage loans, Percentage	9.90%	7.40%
Retail
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 349,157	$ 363,706
Commercial mortgage loans, Percentage	5.20%	5.90%
Commercial mortgage loans
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 6,180,784	$ 5,593,004
Commercial mortgage loans, Percentage	91.50%	90.90%
Agricultural property loans
Commercial Mortgage and Other Loans [Line Items]
Commercial mortgage and agricultural property loans	$ 571,962	$ 562,046
Commercial mortgage loans, Percentage	8.50%	9.10%