Investments Equity Method Investments (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
 12 Months Ended 0 Months Ended 9 Months Ended 12 Months Ended 0 Months Ended 12 Months Ended 3 Months Ended 12 Months Ended 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2012
Cosine [Member]
Dec. 31, 2011
Cosine [Member]
Dec. 31, 2010
Cosine [Member]
Jul. 05, 2011
DGT
Sep. 30, 2012
DGT
Dec. 31, 2012
DGT
Dec. 31, 2011
DGT
Dec. 31, 2010
DGT
Dec. 31, 2012
Other [Member]
Dec. 31, 2011
Other [Member]
Dec. 31, 2010
Other [Member]
Jun. 30, 2012
Other [Member]
Mar. 19, 2012
Fox & Hound [Member]
Dec. 31, 2012
Fox & Hound [Member]
Dec. 31, 2011
Fox & Hound [Member]
Dec. 31, 2010
Fox & Hound [Member]
Dec. 31, 2012
SLI [Member]
Jun. 30, 2012
Steel Excel
Dec. 31, 2012
Steel Excel
Dec. 31, 2011
Steel Excel
Dec. 31, 2010
Steel Excel
May 31, 2012
Steel Excel
Dec. 31, 2011
Steel Partners, Ltd
DGT
Dec. 31, 2010
Steel Partners, Ltd
DGT
Schedule of Equity Method Investments [Line Items]                                                      
SPH's equity in other comprehensive loss $ 0 $ 5,833 $ (737)                                                
Equity method investment, share of capital changes       52 68 6                                          
Equity method investment, quoted market value       9,559 9,320                                            
Shares sold (in shares)             193,305                           2,227,500            
Share sale price             1,933                                        
Investment owned (in shares)               1,977,023                                 4,584,399    
Sale of stock, ownership percentage after transaction (as a percent)               51.10%                           51.10%          
Income (Loss) of associated companies, net of taxes 14,532 (13,593) 8,625 (328) (385) (440)     0 213 886 0 (58) 6     (403) 0 0     13,139 (22,092) (10,439)   231 114
Investment owned, at cost                       4,576 5,156                            
Long Lived Assets Held-for-sale, Impairment Charge                             (580)                        
Payments to acquire equity method investments                               10,923                      
Investment and other income $ 2,347 $ 867 $ 4,418                                 $ 2,000