Allowance for Credit Losses - Summary of Allowance for Credit Losses (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Allowance for credit losses and recorded investment in financing receivables
Balance	$ 4,573	$ 2,572
Provision for credit losses	114	7
Recoveries		3
Write-offs	(227)	(2,137)
Balance	4,460	445
Finance Leases Financing Receivable [Member]
Allowance for credit losses and recorded investment in financing receivables
Balance	439	525
Provision for credit losses	114	7
Recoveries		3
Write-offs	(227)	(90)
Balance	326	445
Balance individually evaluated for impairment	194,791	90,490
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
Balance individually evaluated for impairment	$ 18,923	$ 14,428