v2.4.0.6
Ownership Components of Total Equity (Detail) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2012
Sep. 30, 2011
Sep. 30, 2012
Sep. 30, 2011
Stockholders Equity [Line Items]        
Beginning Balance, January 1, 2012     $ 959,661  
Net income 45,893 40,182 125,753 153,422
Unrealized holding gains and reclassification     56,265  
Foreign currency translation     4,624  
Unrealized loss on interest rate swap     (952)  
Equity component of convertible senior notes, net of income tax and issue costs     3,306  
Capital contribution     16,624  
Acquisition of non-controlling interest     0  
Dividends     (18,200)  
Share exercises and compensation, other     9,130  
Ending Balance, Sept 30, 2012 1,156,211   1,156,211  
AmTrust
       
Stockholders Equity [Line Items]        
Beginning Balance, January 1, 2012     890,563  
Net income     122,674  
Unrealized holding gains and reclassification     56,265  
Foreign currency translation     4,624  
Unrealized loss on interest rate swap     (952)  
Equity component of convertible senior notes, net of income tax and issue costs     3,306  
Acquisition of non-controlling interest     6,900  
Dividends     (18,200)  
Share exercises and compensation, other     9,130  
Ending Balance, Sept 30, 2012 1,074,310   1,074,310  
Non-Controlling Interests
       
Stockholders Equity [Line Items]        
Beginning Balance, January 1, 2012     69,098  
Net income     3,079  
Capital contribution     16,624  
Acquisition of non-controlling interest     (6,900)  
Ending Balance, Sept 30, 2012 $ 81,901   $ 81,901