Allowance for Credit Losses - Summary of Allowance for Credit Losses (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Allowance for credit losses and recorded investment in financing receivables
Financing Receivable, Allowance for Credit Losses	$ 2,272	$ 2,257
Financing Receivable, Allowance for Credit Losses, Provisions	0
Financing Receivable, Allowance for Credit Losses, Recoveries	15
Financing Receivable, Allowance for Credit Losses, Charge-offs	0
Allowance resulting from individual impairment evaluation	2,272
Allowance resulting from collective impairment evaluation	0
Recorded investment in financing receivables
Balance individually evaluated for impairment	114,953
Balance collectively evaluated for impairment	0
Finance Leases Financing Receivable [Member]
Allowance for credit losses and recorded investment in financing receivables
Financing Receivable, Allowance for Credit Losses	225	210
Financing Receivable, Allowance for Credit Losses, Provisions	0
Financing Receivable, Allowance for Credit Losses, Recoveries	15
Financing Receivable, Allowance for Credit Losses, Charge-offs	0
Allowance resulting from individual impairment evaluation	225
Allowance resulting from collective impairment evaluation	0
Recorded investment in financing receivables
Balance individually evaluated for impairment	100,819
Balance collectively evaluated for impairment	0
Notes Receivable [Member]
Allowance for credit losses and recorded investment in financing receivables
Financing Receivable, Allowance for Credit Losses	2,047	2,047
Financing Receivable, Allowance for Credit Losses, Provisions	0
Financing Receivable, Allowance for Credit Losses, Recoveries	0
Financing Receivable, Allowance for Credit Losses, Charge-offs	0
Allowance resulting from individual impairment evaluation	2,047
Allowance resulting from collective impairment evaluation	0
Recorded investment in financing receivables
Balance individually evaluated for impairment	14,134
Balance collectively evaluated for impairment	$ 0