Fair Value Measurements (Narrative) (Details)	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($) broker
Fair Value Measurement [Line Items]
Percentage of portfolio of unadjusted fair values obtained	97.90%
Number of knowledgeable outside security brokers consulted to determine fair value | broker		1
Three Private Equity Funds using NAV	$ 107,700,000
One Private Equity Fund using NAV	700,000
Fair Value, Assets, Level 1 to Level 2 to Level 3 Transfers, Amount	0	$ 0
Unsecured Debt
Fair Value Measurement [Line Items]
Debt instrument, face amount	$ 375,000,000	375,000,000
Minimum
Fair Value Measurement [Line Items]
Liquidating investment, remaining period	1 year
Maximum
Fair Value Measurement [Line Items]
Liquidating investment, remaining period	9 years
Private Equity Funds
Fair Value Measurement [Line Items]
Unfunded commitments	$ 32,000,000
Level 2 | Commercial Mortgage Backed Securities
Fair Value Measurement [Line Items]
Holings in mortgage backed securities	$ 25,200,000	$ 17,600,000