Investments In Securities and Fair Value (Schedule of Cost-method Investments) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Fair​Value​Assets​Measured​On​Nonrecurring​Basis​Reconciliation​Calculation​Roll​Forward [Line Items]
Beginning balance	$ 13,675	$ 8,741
Other than temporary impairment losses, investments	0	0
Observable changes	0	0
Purchases and additional commitments paid	250	6,543
Sales, returns of capital, and other reductions	(30)	(1,609)
Ending balance	13,895	13,675
Real Estate Investment
Fair​Value​Assets​Measured​On​Nonrecurring​Basis​Reconciliation​Calculation​Roll​Forward [Line Items]
Beginning balance	4,987	0
Other than temporary impairment losses, investments	0	0
Observable changes	0	0
Purchases and additional commitments paid	0	5,000
Sales, returns of capital, and other reductions	0	(13)
Ending balance	4,987	4,987
Cost-method Investments
Fair​Value​Assets​Measured​On​Nonrecurring​Basis​Reconciliation​Calculation​Roll​Forward [Line Items]
Beginning balance	8,688	8,741
Other than temporary impairment losses, investments	0	0
Observable changes	0	0
Purchases and additional commitments paid	250	1,543
Sales, returns of capital, and other reductions	(30)	(1,596)
Ending balance	$ 8,908	$ 8,688