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Stock-based Compensation Plans and Awards (Details) (USD $)
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3 Months Ended | 9 Months Ended | 3 Months Ended | 9 Months Ended | 1 Months Ended | 3 Months Ended | 9 Months Ended | 3 Months Ended | 9 Months Ended | |||||||
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Oct. 31, 2013
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Oct. 31, 2012
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Oct. 31, 2013
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Oct. 31, 2012
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Sep. 30, 2013
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Oct. 31, 2013
Stock Options
Black-Scholes option pricing model
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Oct. 31, 2013
Stock Options
Black-Scholes option pricing model
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Oct. 31, 2012
Stock Options
Black-Scholes option pricing model
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Sep. 30, 2013
Stock option with market and service conditions
Mr. Joseph Kennedy
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Jul. 31, 2013
Stock option with market and service conditions
Mr. Joseph Kennedy
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Mar. 31, 2012
Stock option with market and service conditions
Mr. Joseph Kennedy
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Oct. 31, 2013
Stock option with market and service conditions
Mr. Joseph Kennedy
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Apr. 30, 2013
Stock option with market and service conditions
Mr. Joseph Kennedy
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Oct. 31, 2013
Stock option with market and service conditions
Mr. Joseph Kennedy
Monte-Carlo simulation option pricing model
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Oct. 31, 2013
Restricted stock units
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Oct. 31, 2013
Restricted stock units
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| Assumptions used to calculate per-share fair value of stock option at the date of grant | ||||||||||||||||
| Expected life | 6 years 3 months 25 days | 6 years 3 months 18 days | 6 years 8 months 1 day | 10 years | ||||||||||||
| Risk-free interest rate (as a percent) | 2.04% | 1.62% | 1.52% | 2.33% | ||||||||||||
| Expected volatility (as a percent) | 58.00% | 58.00% | 57.00% | 70.00% | ||||||||||||
| Expected dividend yield (as a percent) | 0.00% | 0.00% | 0.00% | |||||||||||||
| Stock price (in dollars per share) | $ 25.00 | $ 10.63 | ||||||||||||||
| Stock-based compensation expense | $ 12,647,000 | $ 7,073,000 | $ 30,570,000 | $ 18,610,000 | $ 600,000 | $ 8,700,000 | $ 21,900,000 | |||||||||
| Granted (in shares) | 800,000 | |||||||||||||||
| Exercise price (in dollars per share) | $ 10.63 | |||||||||||||||
| Period of time that the trailing weighted average stock price must exceed a certain price for the stock award to vest, prior to July, 2017 | 60 days | |||||||||||||||
| Share price, under a sale of the entity, that must be obtained for the stock award to vest prior to July, 2017 (in dollars per share) | $ 21.00 | |||||||||||||||
| Share price that must be obtained for the stock award to vest prior to July, 2017 (in dollars per share) | $ 21.00 | |||||||||||||||
| Vesting term | 4 years | 4 years | 4 years | |||||||||||||
| Weighted-average fair value of stock option granted (in dollars per share) | $ 6.08 | |||||||||||||||
| Lower stock-based compensation expense | $ 1,700,000 | |||||||||||||||