Notes Receivable and Allowance for Losses Past Due Balances Of Mezzanine And Other Notes Receivable (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Forgivable Notes Receivable
Notes Receivable and Allowance for Losses [Line Items]
Total Past Due	$ 1,615	$ 1,465
Current	65,083	50,010
Total Notes Receivable	66,698	51,475
Mezzanine & Other Notes Receivable
Notes Receivable and Allowance for Losses [Line Items]
Total Past Due	0	0
Current	92,618	74,436
Total Notes Receivable	92,618	74,436
Mezzanine & Other Notes Receivable | Senior
Notes Receivable and Allowance for Losses [Line Items]
Total Past Due	0	0
Current	70,616	61,482
Total Notes Receivable	70,616	61,482
Mezzanine & Other Notes Receivable | Subordinated
Notes Receivable and Allowance for Losses [Line Items]
Total Past Due	0	0
Current	18,526	9,336
Total Notes Receivable	18,526	9,336
Mezzanine & Other Notes Receivable | Unsecured
Notes Receivable and Allowance for Losses [Line Items]
Total Past Due	0	0
Current	3,476	3,618
Total Notes Receivable	3,476	3,618
Financing Receivables, 30 to 89 Days Past Due | Forgivable Notes Receivable
Notes Receivable and Allowance for Losses [Line Items]
Total Past Due	24	116
Financing Receivables, 30 to 89 Days Past Due | Mezzanine & Other Notes Receivable
Notes Receivable and Allowance for Losses [Line Items]
Total Past Due	0	0
Financing Receivables, 30 to 89 Days Past Due | Mezzanine & Other Notes Receivable | Senior
Notes Receivable and Allowance for Losses [Line Items]
Total Past Due	0	0
Financing Receivables, 30 to 89 Days Past Due | Mezzanine & Other Notes Receivable | Subordinated
Notes Receivable and Allowance for Losses [Line Items]
Total Past Due	0	0
Financing Receivables, 30 to 89 Days Past Due | Mezzanine & Other Notes Receivable | Unsecured
Notes Receivable and Allowance for Losses [Line Items]
Total Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due | Forgivable Notes Receivable
Notes Receivable and Allowance for Losses [Line Items]
Total Past Due	1,591	1,349
Financing Receivables, Equal to Greater than 90 Days Past Due | Mezzanine & Other Notes Receivable
Notes Receivable and Allowance for Losses [Line Items]
Total Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due | Mezzanine & Other Notes Receivable | Senior
Notes Receivable and Allowance for Losses [Line Items]
Total Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due | Mezzanine & Other Notes Receivable | Subordinated
Notes Receivable and Allowance for Losses [Line Items]
Total Past Due	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due | Mezzanine & Other Notes Receivable | Unsecured
Notes Receivable and Allowance for Losses [Line Items]
Total Past Due	$ 0	$ 0