XML 60 R41.htm IDEA: XBRL DOCUMENT v2.4.0.6
Shareholders' equity (Details) (USD $)
 1 Months Ended 3 Months Ended 11995 Months Ended
Aug. 31, 2011
Mar. 31, 2012
Mar. 31, 3012
Dec. 31, 2011
Increase (Decrease) in Stockholders' Equity [Roll Forward]        
Repurchase of common stock (in shares)   400,000    
Common stock, shares authorized (in shares)   195,000,000   195,000,000
Stock repurchase program, Number of shares authorized to be repurchased (in shares) $ 60,000,000      
Number of shares Treasury stock acquired (in shares)     4,786,521  
Treasury stock acquired, Aggregate purchase price     49,924,000  
Stock repurchase program, Remaining authorized repurchase amount (in shares)   $ 10,076,000    
Series A Convertible Preferred Stock [Member]
        
Increase (Decrease) in Stockholders' Equity [Roll Forward]        
Shares, Beginning balance   80,718    
Repurchase of common stock (in shares)   0    
Conversion of convertible preferred stock (in shares)   22    
Issuance for stock compensation plans (in shares)   0    
Shares, Ending balance   80,696    
Treasury Stock [Member]
        
Increase (Decrease) in Stockholders' Equity [Roll Forward]        
Shares, Beginning balance   4,386,521    
Repurchase of common stock (in shares)   400,000    
Conversion of convertible preferred stock (in shares)   0    
Issuance for stock compensation plans (in shares)   0    
Shares, Ending balance   4,786,521    
Common Stock [Member]
        
Increase (Decrease) in Stockholders' Equity [Roll Forward]        
Shares, Beginning balance   88,844,327    
Repurchase of common stock (in shares)   400,000    
Conversion of convertible preferred stock (in shares)   2,225    
Issuance for stock compensation plans (in shares)   3,104    
Shares, Ending balance   88,449,656