Notes Receivable and Allowance for Losses - Summary of activity related to allowance for losses (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Movement in Valuation Allowances and Reserves [Roll Forward]
Ending balance	$ 5,987		$ 11,546
Forgivable Notes Receivable [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	1,650		1,623
Provisions	2,528		699
Recoveries	(303)		(9)
Write-offs	(305)		(115)
Other	91	[1]	(548)	[1]
Ending balance	3,661		1,650
Mezzanine & Other Notes Receivable [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	9,896		8,927
Provisions	102		969
Recoveries	(875)		0
Write-offs	(6,797)		0
Other	0	[1]	0	[1]
Ending balance	$ 2,326		$ 9,896

[1] Consists of default rate assumption changes