Allowance for Credit Losses (Activity in Allowance for Doubtful Accounts) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	$ 1	$ 15
Provision (reversal of) credit losses	4	(14)
Ending Balance	5	1
Allowance For Doubtful Accounts [Member] | Operating Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	1
Provision (reversal of) credit losses	4	1
Ending Balance	$ 5	1
Valuation Adjustments on Financing Receivables [Member] | Notes Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance		15
Provision (reversal of) credit losses		$ (15)