Net Investment in Sales-Type Leases - Allowance for Credit Losses (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses, beginning of period	$ 169	$ 190	$ 167	$ 607
Current period provision (reversal)	(12)	6	(10)	19
Direct write-downs charged against the allowance	0	0	0	(413)
Recoveries of amounts previously charged off	0	(12)	0	(29)
Allowance for credit losses, end of period	$ 157	$ 184	$ 157	$ 184