Annual report pursuant to Section 13 and 15(d)

Share-Based Compensation - Additional Information (Detail)

v2.4.0.6
Share-Based Compensation - Additional Information (Detail) (USD $)
 12 Months Ended 1 Months Ended 12 Months Ended 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2012
Before Amendment
Dec. 31, 2012
After Amendment
Dec. 31, 2011
Real Goods Solar
Dec. 31, 2010
Real Goods Solar
Dec. 31, 2012
Long Term Incentive Plan 2009
Dec. 31, 2012
Long Term Incentive Plan 2009
Class A Common Stock
Mar. 05, 2012
Long-Term Incentive Plan 1999
Employee
Dec. 31, 2009
Long-Term Incentive Plan 1999
Dec. 31, 2009
Long-Term Incentive Plan 1999
Maximum
Dec. 31, 2009
Long-Term Incentive Plan 1999
Minimum
Dec. 31, 2010
Long-Term Incentive Plan 1999
Chief Executive Officer
Nov. 04, 2010
Long-Term Incentive Plan 1999
Chief Executive Officer
Dec. 31, 2012
Long Term Incentive Plan, Two Thousand Nine and Nineteen Ninety Nine
Dec. 31, 2012
Employee Stock Option
Dec. 31, 2012
Non Employee Board Member Stock Options
Dec. 31, 2009
Stock Options
Long-Term Incentive Plan 1999
Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                      
Number of shares that may be issued                 3,000,000                    
Plan termination date               Apr. 23, 2019                      
Rate at which options vest and become exercisable per month 2.00%                                    
Period over which options vest and become exercisable 50 months                                    
Compensation expense related to share-based payment awards                                 5 years 2 years  
Granted Stock Options expiration date       7 years 10 years         2 years                  
Fair value assumptions dividend per share $ 0.15                                    
Number of employees                   7                  
Total incremental share-based compensation cost                   $ 100,000                  
Options vested, extended expiration date                             200,000        
Incremental share-based compensation cost                           93,000          
Number of employees award granted                                     49
Revised exercise price per share                     $ 5.00                
Total incremental share-based compensation cost recognizable over 2009 through 2013                     212,000                
Total incremental share-based compensation cost recognizable, year                       2009 2013            
Cash from stock options exercised   100,000                                  
Weighted-average grant-date fair value of options granted $ 2.39 $ 2.32 $ 3.42                                
Total intrinsic value of options exercised   100,000 100,000                                
Total fair value of shares vested 800,000 800,000 1,100,000                                
Share-based compensation expense 1,013,000 1,540,000 1,609,000     500,000 100,000                        
Income tax benefit recognized for share-based compensation 400,000 600,000 600,000                                
Unrecognized cost related to nonvested shared-based compensation                               $ 1,000,000      
Expected cost to be recognized over a weighted-average period                               2 years 9 months 7 days