Investments in Partnerships and LLCs (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended	9 Months Ended	12 Months Ended									9 Months Ended
	Jan. 31, 2012	Sep. 30, 2013	Dec. 31, 2009 agreement company	Dec. 31, 2012	Sep. 30, 2013 EM 646 [Member]	Sep. 30, 2013 EM 646 [Member] Minimum [Member]	Sep. 30, 2013 EM 646 [Member] Maximum [Member]	Sep. 30, 2013 Unconsolidated Variable Interest Entities [Member] Minimum [Member]	Sep. 30, 2013 Unconsolidated Variable Interest Entities [Member] Maximum [Member]	Sep. 30, 2013 Variable Interest Entity, Primary Beneficiary [Member]	Dec. 31, 2012 Variable Interest Entity, Primary Beneficiary [Member]	Sep. 30, 2013 Variable Interest Entity, Not Primary Beneficiary [Member]	Sep. 30, 2012 Variable Interest Entity, Not Primary Beneficiary [Member]
Noncontrolling Interest [Line Items]
Ownership percentage (percent)						20.00%		20.00%
Parent ownership percentage (percent)		60.00%			58.20%		58.20%		50.00%
Number of separate agreements with unrelated third parties (agreements)			2
Number of limited liabilities formed (companies)			2
Real estate inventory		$ 204,040		$ 171,044						$ 33,707	$ 32,659
Gain on sale of property	2,731
Gain recognized in consolidated statement of operations		1,639
Contributions to unconsolidated entities												$ 99	$ 98