Net Investment in Sales-Type Leases allowance credit loss rollforward (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Mar. 31, 2012	Mar. 31, 2011
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Allowance for credit losses, beginning of period			$ 284	$ 411	$ 659	$ 353
Current period provision (reversal)	4	(7)	426	(16)
Direct write-downs charged against the allowance	0	0	0	0
Recoveries of amounts previously charged off	(26)	(24)	(73)	(73)
Allowance for credit losses, end of period	$ 637	$ 322	$ 637	$ 322	$ 659	$ 353