Mortgage Loans on Real Estate (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) loan segment properties	Dec. 31, 2022 USD ($) loan properties	Dec. 31, 2021 USD ($)
Loans and Leases Receivable Disclosure [Line Items]
Number of portfolio segments that make up financing receivables | segment	3
Commitments outstanding	$ 786,400
Accrued interest receivable	$ 69,500	$ 58,200
Financing Receivable, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Accrued investment income (2023 and 2022 include $2,862 and $3,444 related to consolidated variable interest entities)
Real estate acquired through foreclosure, number of units | properties	12	0
Real estate acquired through foreclosure	$ 6,500
Non-accrual status, number of loans | loan	155	59
Interest income recognized on non-accrual loans	$ 3,000	$ 670	$ 36
Number of significant loan modifications | loan	0
Minimum
Loans and Leases Receivable Disclosure [Line Items]
Number of days past due, nonperforming	90 days
Commercial Mortgage Loans
Loans and Leases Receivable Disclosure [Line Items]
Accrued interest receivable written off	$ 0	0
Agricultural Mortgage Loans
Loans and Leases Receivable Disclosure [Line Items]
Accrued interest receivable written off	0	0
Residential Mortgage Loans
Loans and Leases Receivable Disclosure [Line Items]
Accrued interest receivable written off	$ 0	$ 0