Fair Value Measurements (Summarize Changes in Level 3 Assets) (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, impairments		$ 0
Securities transferred into or out of level 3, net	$ 0
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	19,546,000	15,558,000
Assets, earnings	623,000	1,073,000
Assets, other comprehensive income	0	0
Impairment of Intangible Assets (Excluding Goodwill)	0
Assets, purchases	0	3,000,000
Assets, (sales)	(1,569,000)	(1,085,000)
Assets, maturities	0
Assets. transfers out		1,000,000
Securities transferred into or out of level 3, net	0
Assets, ending balance	18,600,000	19,546,000
Level 3 | Debt securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	1,000,000	0
Assets, earnings	0	0
Assets, other comprehensive income	0	0
Impairment of Intangible Assets (Excluding Goodwill)	0
Assets, impairments		0
Assets, purchases	0	0
Assets, (sales)	(1,000,000)	0
Assets, maturities	0
Assets. transfers out		1,000,000
Securities transferred into or out of level 3, net	0
Assets, ending balance	0	1,000,000
Level 3 | Asset-backed
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	0	0
Assets, earnings		0
Assets, other comprehensive income		0
Assets, impairments		0
Assets, purchases		0
Assets, (sales)		0
Assets, maturities		0
Assets. transfers out		0
Assets, ending balance		0
Level 3 | Real estate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	18,546,000	15,558,000
Assets, earnings	615,000	1,054,000
Assets, other comprehensive income	0	0
Assets, impairments	0	0
Assets, purchases	0	3,000,000
Assets, (sales)	(561,000)	(1,066,000)
Assets, maturities		0
Assets. transfers out	0	0
Assets, ending balance	18,600,000	18,546,000
Level 3 | Common stock
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	9,215,000	9,053,000
Assets, earnings	613,000	1,228,000
Assets, other comprehensive income	0	0
Assets, impairments	0	0
Assets, purchases	0	0
Assets, (sales)	(561,000)	(1,066,000)
Assets. transfers out	0	0
Assets, ending balance	9,267,000	9,215,000
Level 3 | Preferred stocks
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	9,331,000	6,505,000
Assets, earnings	2,000	(174,000)
Assets, other comprehensive income	0	0
Assets, impairments	0	0
Assets, purchases	0	3,000,000
Assets, (sales)	0	0
Assets. transfers out	0	0
Assets, ending balance	9,333,000	9,331,000
Level 3 | Arbitrage trading account
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	0	0
Assets, earnings	8,000	19,000
Assets, other comprehensive income	0	0
Impairment of Intangible Assets (Excluding Goodwill)	0
Assets, impairments		0
Assets, purchases	0	0
Assets, (sales)	(8,000)	(19,000)
Assets, maturities	0
Securities transferred into or out of level 3, net	0
Assets, ending balance	0	0
Level 3 | Corporate
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Assets, beginning balance	1,000,000	0
Assets, earnings	0	0
Assets, other comprehensive income	0	0
Impairment of Intangible Assets (Excluding Goodwill)	0	0
Assets, purchases	0	0
Assets, (sales)	(1,000,000)	0
Assets, maturities	0	0
Securities transferred into or out of level 3, net	0	1,000,000
Assets, ending balance	$ 0	$ 1,000,000