Net Investment in Sales-Type Leases allowance credit loss rollforward (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses, beginning of period	$ 167	$ 607
Current period provision (reversal)	2	13
Direct write-downs charged against the allowance	0	(413)
Recoveries of amounts previously charged off	0	(17)
Allowance for credit losses, end of period	$ 169	$ 190