Notes Receivable and Allowance for Losses Narrative (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) category	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Notes Receivable and Allowance for Losses [Line Items]
Number of categories, credit losses for notes receivable | category			2
Notes receivable	$ 113,908,000		$ 113,908,000		$ 94,444,000
Loan reserves	7,749,000		7,749,000		6,765,000
Amortization expense	2,986,000	$ 3,108,000	8,707,000	$ 8,793,000
Forgivable Notes Receivable
Notes Receivable and Allowance for Losses [Line Items]
Notes receivable	51,401,000		51,401,000		44,333,000
Loan reserves	5,052,000		5,052,000		4,615,000
Amortization expense	2,300,000	2,100,000	6,700,000	6,000,000
Mezzanine & Other Notes Receivable
Notes Receivable and Allowance for Losses [Line Items]
Notes receivable	62,507,000		62,507,000		50,111,000
Loan reserves	2,697,000		2,697,000		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			1,400,000	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	$ 1,100,000		$ 1,100,000		$ 1,400,000