Investment in Unconsolidated Ventures - Summarized Balance Sheet Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Venture Assets	$ 309,276	$ 240,490
Venture Borrowings	143,988	102,247
Venture Equity	128,495	110,447
Investment in venture	85,325	65,005
242, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Venture Assets	27,647	33,021
Venture Borrowings	0	6,940
Venture Equity	25,822	21,789
Investment in venture	12,239	10,098
CL Ashton Woods [Member]
Schedule of Equity Method Investments [Line Items]
Venture Assets	8,453	13,269
Venture Borrowings	0	0
Venture Equity	5,671	11,453
Investment in venture	2,620	6,015
CL Realty [Member]
Schedule of Equity Method Investments [Line Items]
Venture Assets	8,246	7,960
Venture Borrowings	0	0
Venture Equity	8,084	7,738
Investment in venture	4,042	3,869
CREA FMF [Member]
Schedule of Equity Method Investments [Line Items]
Venture Assets	57,193	40,014
Venture Borrowings	49,960	29,660
Venture Equity	4,780	5,987
Investment in venture	4,309	5,516
Elan 99, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Venture Assets	25,572	10,070
Venture Borrowings	5,726	1
Venture Equity	15,885	9,643
Investment in venture	14,297	8,679
FOR/SR Forsyth LLC [Member]
Schedule of Equity Method Investments [Line Items]
Venture Assets	6,300	0
Venture Borrowings	0	0
Venture Equity	6,300	0
Investment in venture	5,670	0
FMF Littleton [Member]
Schedule of Equity Method Investments [Line Items]
Venture Assets	43,828	26,953
Venture Borrowings	15,665	0
Venture Equity	24,585	24,435
Investment in venture	6,324	6,287
FMF Peakview [Member]
Schedule of Equity Method Investments [Line Items]
Venture Assets	48,984	43,638
Venture Borrowings	29,426	23,070
Venture Equity	16,924	17,464
Investment in venture	3,467	3,575
HM Stonewall Estates [Member]
Schedule of Equity Method Investments [Line Items]
Venture Assets	3,054	3,750
Venture Borrowings	0	669
Venture Equity	3,054	3,081
Investment in venture	1,822	1,752
LM Land Holdings [Member]
Schedule of Equity Method Investments [Line Items]
Venture Assets	33,397	25,561
Venture Borrowings	8,015	4,448
Venture Equity	23,679	18,500
Investment in venture	11,033	9,322
MRECV DT Holdings LLC [Member]
Schedule of Equity Method Investments [Line Items]
Venture Assets	3,899	0
Venture Borrowings	0	0
Venture Equity	3,899	0
Investment in venture	3,510	0
MRECV Edelweiss LLC [Member]
Schedule of Equity Method Investments [Line Items]
Venture Assets	2,000	0
Venture Borrowings	0	0
Venture Equity	2,000	0
Investment in venture	1,800	0
MREC VH Juniper Ridge LLC [Member]
Schedule of Equity Method Investments [Line Items]
Venture Assets	1,796	0
Venture Borrowings	0	0
Venture Equity	1,796	0
Investment in venture	1,616	0
Miramonte Boulder Pass, LLC [Member] [Domain]
Schedule of Equity Method Investments [Line Items]
Venture Assets	12,429	0
Venture Borrowings	5,360	0
Venture Equity	5,533	0
Investment in venture	5,403	0
PSW Communities [Member]
Schedule of Equity Method Investments [Line Items]
Venture Assets	14,060	16,045
Venture Borrowings	6,880	10,515
Venture Equity	6,557	4,415
Investment in venture	4,123	3,924
Temco [Member]
Schedule of Equity Method Investments [Line Items]
Venture Assets	5,813	11,756
Venture Borrowings	0	0
Venture Equity	5,232	11,556
Investment in venture	2,616	5,778
Other ventures [Member]
Schedule of Equity Method Investments [Line Items]
Venture Assets	6,605	8,453
Venture Borrowings	22,956	26,944
Venture Equity	(31,306)	(25,614)
Investment in venture	$ 434	$ 190