Allowance for Credit Losses - Summary of Allowance for Credit Losses (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Allowance for credit losses and recorded investment in financing receivables
Balance	$ 4,573	$ 2,572
Provision for credit losses	8	7
Recoveries		3
Write-offs		(501)
Balance	4,581	2,081
Finance Leases Financing Receivable [Member]
Allowance for credit losses and recorded investment in financing receivables
Balance	439	525
Provision for credit losses	8	7
Recoveries		3
Write-offs		(75)
Balance	447	460
Balance individually evaluated for impairment	202,559	89,845
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		(426)
Balance	4,134	1,621
Balance individually evaluated for impairment	$ 14,128	$ 15,790