Net Income per Share - Earnings Attributable to Common Shareholders and Weighted Average Common Shares Outstanding (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings available to common shareholders:
Consolidated net income	$ 12,897	$ (380)	$ 19,137	$ 4,588
Less: Net income attributable to noncontrolling interests	(1,067)	(323)	(2,815)	(1,678)
Net income attributable to Forestar Group Inc.	$ 11,830	$ (703)	$ 16,322	$ 2,910
Weighted average common shares outstanding - basic	35,410	35,233	35,341	35,204
Dilutive effect of stock options, restricted stock and equity-settled awards	662	0	608	233
Weighted average common shares outstanding - diluted	36,072	35,233	35,949	35,437
Anti-dilutive awards excluded from diluted weighted average shares	1,764	2,661	2,022	2,582