Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity (Stock Option Exercise Price Range) (Details)

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Stockholders' Equity (Stock Option Exercise Price Range) (Details) (Stock Options [Member], USD $)
12 Months Ended
Dec. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Number of Outstanding Options (options) 6,132,641
Weighted Average Remaining Contractual Term (years) 4 years 10 months 28 days
Options Outstanding, Weighted Average Exercise Price Per Share (dollars per share) $ 6.65
Number of Options Exercisable (number of options) 4,422,877
Options Exercisable, Weighted Average Exercise Price Per Share (dollars per share) $ 7.21
$0.60 - $5.20
 
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Number of Outstanding Options (options) 2,313,165
Weighted Average Remaining Contractual Term (years) 6 years 0 months 4 days
Options Outstanding, Weighted Average Exercise Price Per Share (dollars per share) $ 2.66
Number of Options Exercisable (number of options) 1,084,768
Options Exercisable, Weighted Average Exercise Price Per Share (dollars per share) $ 1.80
Exercise price range, lower range limit (dollars per share) $ 0.60
Exercise price range, upper range limit (dollars per share) $ 5.20
$5.20 - $8.63
 
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Number of Outstanding Options (options) 1,573,714
Weighted Average Remaining Contractual Term (years) 3 years 4 months 6 days
Options Outstanding, Weighted Average Exercise Price Per Share (dollars per share) $ 7.22
Number of Options Exercisable (number of options) 1,500,998
Options Exercisable, Weighted Average Exercise Price Per Share (dollars per share) $ 7.19
Exercise price range, lower range limit (dollars per share) $ 5.20
Exercise price range, upper range limit (dollars per share) $ 8.63
$8.63 - $10.50
 
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Number of Outstanding Options (options) 940,446
Weighted Average Remaining Contractual Term (years) 4 years 10 months 21 days
Options Outstanding, Weighted Average Exercise Price Per Share (dollars per share) $ 9.62
Number of Options Exercisable (number of options) 756,372
Options Exercisable, Weighted Average Exercise Price Per Share (dollars per share) $ 9.72
Exercise price range, lower range limit (dollars per share) $ 8.63
Exercise price range, upper range limit (dollars per share) $ 10.50
$10.50 - $11.87
 
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Number of Outstanding Options (options) 1,305,316
Weighted Average Remaining Contractual Term (years) 4 years 10 months 10 days
Options Outstanding, Weighted Average Exercise Price Per Share (dollars per share) $ 10.89
Number of Options Exercisable (number of options) 1,080,739
Options Exercisable, Weighted Average Exercise Price Per Share (dollars per share) $ 10.91
Exercise price range, lower range limit (dollars per share) $ 10.50
Exercise price range, upper range limit (dollars per share) $ 11.87