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Stock-based Compensation Plans and Awards (Details) (USD $)
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3 Months Ended | 1 Months Ended | 3 Months Ended | 1 Months Ended | 3 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Mar. 31, 2014
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Mar. 31, 2013
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Dec. 31, 2013
ESPP
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Mar. 31, 2014
ESPP
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Mar. 31, 2014
ESPP
Black-Scholes option pricing model
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Dec. 31, 2013
ESPP
Maximum
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Mar. 31, 2014
Stock Options
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Mar. 31, 2013
Stock Options
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Mar. 31, 2014
Stock Options
Black-Scholes option pricing model
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Mar. 31, 2013
Stock Options
Black-Scholes option pricing model
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Mar. 31, 2013
Stock Options
Minimum
Black-Scholes option pricing model
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Mar. 31, 2013
Stock Options
Maximum
Black-Scholes option pricing model
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Mar. 31, 2014
Restricted stock units
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Mar. 31, 2013
Restricted stock units
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| Stock-based Compensation Plans and Awards | ||||||||||||||
| Percentage of eligible compensation to purchase common stock through payroll deductions (as a percent) | 15.00% | |||||||||||||
| Shares of common stock reserved for issuance | 4,000,000 | |||||||||||||
| Amount of eligible compensation per calendar year to purchase common stock | $ 25,000 | |||||||||||||
| Offering period | 6 months | |||||||||||||
| Exercise price as a percentage of the fair market value of the common stock | 85.00% | |||||||||||||
| Assumptions used to calculate per-share fair value of award | ||||||||||||||
| Expected life | 6 months | 6 years 29 days | 5 years 11 months 26 days | 6 years 3 months 25 days | ||||||||||
| Risk-free interest rate, minimum (as a percent) | 1.71% | 0.99% | ||||||||||||
| Risk-free interest rate, maximum (as a percent) | 1.82% | 1.19% | ||||||||||||
| Risk-free interest rate (as a percent) | 0.08% | |||||||||||||
| Expected volatility, minimum (as a percent) | 57.00% | |||||||||||||
| Expected volatility, maximum (as a percent) | 58.00% | |||||||||||||
| Expected volatility (as a percent) | 42.00% | 59.00% | ||||||||||||
| Expected dividend yield (as a percent) | 0.00% | 0.00% | 0.00% | |||||||||||
| Vesting term | 4 years | |||||||||||||
| Contributions from employees withheld | 900,000 | |||||||||||||
| Stock-based compensation expense | $ 17,392,000 | $ 6,524,000 | $ 300,000 | $ 3,500,000 | $ 1,700,000 | $ 13,600,000 | $ 4,800,000 | |||||||
| Common stock issued (in shares) | 0 | |||||||||||||