Notes Receivable and Allowance for Losses - Schedule of notes receivable (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total notes receivable	$ 50,389	$ 56,234
Allowance for losses on non-impaired loans	5,201	3,257
Allowance for losses on receivables specifically evaluated for impairment	786	8,289
Total loan reserves	5,987	11,546
Net carrying value	44,402	44,688
Current portion, net	3,961	12,816
Long-term portion, net	40,441	31,872
Senior [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total notes receivable	10,152	18,052
Subordinated [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total notes receivable	3,863	14,152
Unsecured [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total notes receivable	36,374	24,030
Forgivable Notes Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total notes receivable	32,379	20,625
Allowance for losses on non-impaired loans	3,661	1,650
Allowance for losses on receivables specifically evaluated for impairment	0	0
Total loan reserves	3,661	1,650	1,623
Net carrying value	28,718	18,975
Current portion, net	124	361
Long-term portion, net	28,594	18,614
Forgivable Notes Receivable [Member] | Senior [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total notes receivable	0	0
Forgivable Notes Receivable [Member] | Subordinated [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total notes receivable	0	0
Forgivable Notes Receivable [Member] | Unsecured [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total notes receivable	32,379	20,625
Mezzanine & Other Notes Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total notes receivable	18,010	35,609
Allowance for losses on non-impaired loans	1,540	1,607
Allowance for losses on receivables specifically evaluated for impairment	786	8,289
Total loan reserves	2,326	9,896	8,927
Net carrying value	15,684	25,713
Current portion, net	3,837	12,455
Long-term portion, net	11,847	13,258
Mezzanine & Other Notes Receivable [Member] | Senior [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total notes receivable	10,152	18,052
Mezzanine & Other Notes Receivable [Member] | Subordinated [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total notes receivable	3,863	14,152
Mezzanine & Other Notes Receivable [Member] | Unsecured [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total notes receivable	$ 3,995	$ 3,405