Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenues	$ 38,500	$ 30,900
Cost of sales	30,700	22,600
Selling, general and administrative expense	5,700	24,100
Equity in earnings of unconsolidated ventures	(600)	(7,000)
Gain on sale of assets	(900)	0
Interest expense	0	2,100
Interest and other income	(1,300)	(600)
INCOME (LOSS) FROM CONTINUING OPERATIONS BEFORE TAXES	4,900	(10,300)
Income tax expense	1,000	12,500
NET INCOME (LOSS) FROM CONTINUING OPERATIONS	3,900	(22,800)
INCOME FROM DISCONTINUED OPERATIONS, NET OF TAXES	0	7,200
CONSOLIDATED NET INCOME (LOSS)	3,900	(15,600)
Less: Net income attributable to noncontrolling interests	600	2,000
NET INCOME (LOSS) ATTRIBUTABLE TO FORESTAR GROUP INC.	$ 3,300	$ (17,600)
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING
Basic (in shares)	41,952,493	41,957,424
Diluted (in shares)	41,958,699	41,957,424
NET INCOME (LOSS) PER BASIC SHARE
Continuing operations, basic (usd per share)	$ 0.08	$ (0.59)
Discontinued operations, basic (usd per share)	0.00	0.17
NET INCOME (LOSS) PER BASIC SHARE (usd per share)	0.08	(0.42)
NET INCOME (LOSS) PER DILUTED SHARE
Continuing operations, diluted (usd per share)	0.08	(0.59)
Discontinued operation, diluted (usd per share)	0.00	0.17
NET INCOME (LOSS) PER DILUTED SHARE (usd per share)	$ 0.08	$ (0.42)