Disposal of Assets (Narrative) (Details) - USD ($)			1 Months Ended	3 Months Ended		6 Months Ended
	Jun. 29, 2021	Apr. 03, 2020	May 31, 2019	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from sale of assets							$ 1,000
Gain on sale/disposal of assets, net							1,000
Current notes receivable				$ 22,400,000		$ 22,400,000		$ 22,400,000
Charter DMN Holdings, LP [Member] | Dallas, Texas [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sale of real estate assets, amount			$ 28,000,000
Proceeds from sale of assets			4,597,000
Real estate assets selling costs			$ 1,000,000
Notes receivable term			2 years
Long-term note receivable			$ 22,400,000
Additional contingency payment receivable if certain conditions are met			1,000,000
Gain on sale/disposal of assets, net			$ 25,908,000
Interest rate on promissory note during first year						3.50%
Interest rate on promissory note during second year						4.50%
Interest rate on unpaid original principal balance of Promissory Note	4.50%
Interest income				$ 251,000	$ 271,000	$ 500,000	$ 520,000
Allowance for notes receivable									$ 0	$ 0
Third Modification Agreement [Member] | Charter DMN Holdings, LP [Member] | Dallas, Texas [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Interest rate on unpaid original principal balance of Promissory Note						6.50%
Note receivable, due date						Jul. 29, 2022
Second Promissory Note [Member] | Charter DMN Holdings, LP [Member] | Dallas, Texas [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Current notes receivable		$ 375,000
Note receivable, due date		Jun. 30, 2021
Second Promissory Note [Member] | Charter DMN Holdings, LP [Member] | Dallas, Texas [Member] | Deferred Purchaser's Interest Payment [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Current notes receivable		$ 195,000
Second Promissory Note [Member] | Charter DMN Holdings, LP [Member] | Dallas, Texas [Member] | 2019 Real Property Tax Reconciliation Payment Due from Purchaser [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Current notes receivable		$ 180,000