Notes Receivable and Allowance for Losses Narrative (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) category	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Notes Receivable and Allowance for Losses [Line Items]
Number of categories, credit losses for notes receivable | category			2
Notes receivable	$ 108,427,000		$ 108,427,000		$ 94,444,000
Loan reserves	7,997,000		7,997,000		6,765,000
Amortization expense	2,956,000	$ 2,995,000	5,721,000	$ 5,685,000
Forgivable Notes Receivable
Notes Receivable and Allowance for Losses [Line Items]
Notes receivable	52,200,000		52,200,000		44,300,000
Loan reserves	5,136,000		5,136,000		4,615,000
Amortization expense	2,200,000	2,100,000	4,400,000	3,900,000
Mezzanine & Other Notes Receivable
Notes Receivable and Allowance for Losses [Line Items]
Notes receivable	56,260,000		56,260,000		50,111,000
Loan reserves	2,861,000		2,861,000		2,150,000
Mezzanine & Other Notes Receivable | Impaired Loans
Notes Receivable and Allowance for Losses [Line Items]
Impaired receivables, recorded investment	1,900,000		1,900,000		800,000
Impaired receivables, related allowance	1,600,000		1,600,000		800,000
Average notes receivable, nonaccrual status			800,000	800,000
Interest income, impaired loans	0	$ 0	43,000	$ 33,000
Mezzanine & Other Notes Receivable | Non-impaired Loans
Notes Receivable and Allowance for Losses [Line Items]
Loan reserves	$ 1,200,000		$ 1,200,000		$ 1,400,000