XML 14 R1.htm IDEA: XBRL DOCUMENT v3.19.2
Document and Entity Information - shares
9 Months Ended
Jun. 30, 2019
Jul. 24, 2019
Entity Information [Line Items]    
Entity Current Reporting Status Yes  
Document Type 10-Q  
Document Period End Date Jun. 30, 2019  
Amendment Flag false  
Document Fiscal Period Focus Q3  
Document Fiscal Year Focus 2019  
Entity Registrant Name FORESTAR GROUP INC.  
Entity Central Index Key 0001406587  
Current Fiscal Year End Date --09-30  
Entity Filer Category Accelerated Filer  
Entity Common Stock, Shares Outstanding   41,959,866
Entity Shell Company false  
Entity Emerging Growth Company false  
Entity Small Business false  
Common Stock [Member]    
Entity Information [Line Items]    
Trading Symbol FOR