Allowance for Credit Losses (Activity in Allowance for Doubtful Accounts) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit losses	$ 2	$ 1
Allowance For Doubtful Accounts [Member] | Operating Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	5
Provision for credit losses	2	1
Ending Balance	$ 7	$ 1