Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity (Narrative) (Details)

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Stockholders' Equity (Narrative) (Details) (USD $)
1 Months Ended 3 Months Ended 9 Months Ended 1 Months Ended 9 Months Ended 9 Months Ended
Aug. 31, 2014
Sep. 30, 2014
Sep. 30, 2014
Sep. 30, 2013
Oct. 30, 2014
Subsequent Event
Sep. 30, 2014
Stock Options
Sep. 30, 2013
Stock Options
Sep. 30, 2014
Restricted Stock
Sep. 30, 2014
2002 Stock Incentive Plan
Stock Options
Sep. 30, 2014
Employee Stock Purchase Plan
Sep. 30, 2013
Employee Stock Purchase Plan
Sep. 30, 2014
Employee Stock Purchase Plan
Stock Options
Sep. 30, 2013
Employee Stock Purchase Plan
Stock Options
Sep. 30, 2014
Certain Directors
2002 Stock Incentive Plan
Sep. 30, 2014
Employees
Sep. 30, 2014
Vesting Period One
2002 Stock Incentive Plan
Stock Options
Sep. 30, 2014
Vesting Period Two
2002 Stock Incentive Plan
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                                  
Award Vesting Period               3 years           1 year 4 years 6 months 42 months
Award Vesting Rights, Percentage                               12.50% 2.08%
Award Vesting Rights           1/8 on the six month anniversary of the date of grant, and 1/48 each month thereafter for 42 months                      
Award Expiration Period           10 years                      
Weighted-average grant date fair value of stock options           $ 47.44                      
Intrinsic value of options exercised           $ 14,700,000 $ 3,600,000                    
Unrecognized compensation cost           14,600,000                      
Weighted-average period in which cost is expected to be recognized           2 years 3 months 18 days   1 year 5 months 16 days                  
Net proceeds from employee stock purchase plan                       4,100,000 2,300,000        
Shares available for future option grants                 1,100,000                
Unrecognized compensation cost, restricted stock               2,300,000                  
Employee Stock Purchase Plan                                  
Shares allowed to purchase in employee stock purchase plan                   1,250              
Offering period of shares in employee stock purchase plan                   6 months              
Percentage of purchase price of stock                   85.00%              
Discount rate                   15.00%              
Shares issued in period                   2,230 5,016            
Stock-based compensation     8,795,000 4,149,000           43,515 37,000            
Shares available for future purchases                   77,285              
Corporate Share Repurchase                                  
Stock repurchase, authorized amount 200,000,000                                
Stock repurchase, maximum period 1 year                                
Stock repurchase, shares   692,800 692,800   110,000                        
Stock repurchase, value   $ 38,500,000 $ 38,500,000   $ 5,000,000