Commitments and Contingencies (Letter of Credit) (Narrative) (Details) - Letter of Credit [Member] - Bank of America Syndicate [Member] $ in Millions	Mar. 31, 2021 USD ($)
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	$ 2.1
Performance Guarantee [Member]
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	$ 1.6