Allowance for Credit Losses - Summary of Allowance for Credit Losses (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Allowance for credit losses and recorded investment in financing receivables
Balance	$ 4,573	$ 2,572
Provision for credit losses	162	8
Recoveries		3
Write-offs	(235)	(2,137)
Balance	4,500	446
Finance Leases Financing Receivable [Member]
Allowance for credit losses and recorded investment in financing receivables
Balance	439	525
Provision for credit losses	162	8
Recoveries		3
Write-offs	(235)	(90)
Balance	366	446
Notes Receivable [Member]
Allowance for credit losses and recorded investment in financing receivables
Balance	4,134	2,047
Provision for credit losses	0	0
Recoveries		0
Write-offs	0	(2,047)
Balance	$ 4,134	$ 0