Receivables (Narrative) (Details)	3 Months Ended
	Mar. 31, 2018 USD ($) payment
Receivables [Abstract]
Number of missed payments before delinquent | payment	3
Typical financing period	12 months
Credit amount requiring additional analysis	$ 250,000
Average period of adjudication	18 months
Installment receivable purchased from DLL	$ 1,073,000