Receivables (Aging of past due financing receivables) (Details) $ in Thousands	Sep. 30, 2020 USD ($)
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	$ 3,796
Current	41,543
Total Financing Receivables	45,339
Recognized Revenue [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	3,163
Current	31,191
Total Financing Receivables	34,354
Deferred Revenue [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	633
Current	10,352
Total Financing Receivables	10,985
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	911
Financing Receivables, 30 to 59 Days Past Due [Member] | Recognized Revenue [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	599
Financing Receivables, 30 to 59 Days Past Due [Member] | Deferred Revenue [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	312
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	386
Financing Receivables, 60 to 89 Days Past Due [Member] | Recognized Revenue [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	281
Financing Receivables, 60 to 89 Days Past Due [Member] | Deferred Revenue [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	105
Financing Receivables, 90 to 120 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	242
Financing Receivables, 90 to 120 Days Past Due [Member] | Recognized Revenue [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	193
Financing Receivables, 90 to 120 Days Past Due [Member] | Deferred Revenue [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	49
Financing Receivables, Greater Than 120 Days Past Due [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	2,257
Financing Receivables, Greater Than 120 Days Past Due [Member] | Recognized Revenue [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	2,090
Financing Receivables, Greater Than 120 Days Past Due [Member] | Deferred Revenue [Member]
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	$ 167