Receivables (Aging of Installment Receivables) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 873	$ 832
0-30 Days Past Due	7	18
31-60 Days Past Due	0	12
61-90 Days Past Due	0	2
90 Days Past Due	4,236	3,848
Total Installment Receivables Past Due	5,116	4,712
U.S.
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	0	0
0-30 Days Past Due	0	0
31-60 Days Past Due	0	0
61-90 Days Past Due	0	0
90 Days Past Due	4,234	3,762
Total Installment Receivables Past Due	4,234	3,762
CANADA
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	873	832
0-30 Days Past Due	7	18
31-60 Days Past Due	0	12
61-90 Days Past Due	0	2
90 Days Past Due	2	86
Total Installment Receivables Past Due	$ 882	$ 950