v2.4.0.6
Capital Stock (Details) (USD $)
12 Months Ended 0 Months Ended 1 Months Ended 12 Months Ended 1 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Nov. 15, 2011
3 7/8% Convertible Senior Notes due 2011 upon maturity
Nov. 30, 2011
3 7/8% Convertible Senior Notes due 2011 upon maturity
Jun. 30, 2012
Common Stock Par Value
Feb. 28, 2011
Common Stock Par Value
Dec. 31, 2012
Common Stock Par Value
Dec. 31, 2011
Common Stock Par Value
Dec. 31, 2012
Funds [Member]
Capital Stock                    
Stock repurchased, shares                   3,700,000
Number of shares of common stock issued and sold in an underwritten public offering           5,980,000 5,563,000      
Issuance of common stock $ 342,469,000 $ 299,558,000       $ 342,500,000   $ 1,495,000 $ 1,627,000  
Aggregate shares of common stock issued for the conversion value in excess of the principal amount       943,714 943,714          
Principal amount repaid       230,000,000            
Interest rate (as a percent) 9.00%   7.125% 3.875% 3.875%          
Accumulated Other Comprehensive Income                    
Foreign currency translation 23,441,000 21,066,000                
Unrealized gain on marketable debt securities 807,000 2,103,000                
Other (894,000) (1,107,000)                
Total accumulated other comprehensive income $ 23,354,000 $ 22,062,000