Selected Balance Sheet Data (Investments in Partnerships) (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Schedule of Equity Method Investments [Line Items]
Total	$ 600	$ 570
Signison [Member]
Schedule of Equity Method Investments [Line Items]
Total	358	418
Other Investment [Member]
Schedule of Equity Method Investments [Line Items]
Total	$ 242	$ 152