Annual report pursuant to Section 13 and 15(d)

Stock-based Compensation Plans and Awards - Schedule of assumptions used for estimating the per-share fair value of stock options (Details)

v2.4.1.9
Stock-based Compensation Plans and Awards - Schedule of assumptions used for estimating the per-share fair value of stock options (Details) (Black-Scholes option pricing model, Stock options)
11 Months Ended 12 Months Ended
Dec. 31, 2013
Dec. 31, 2014
Jan. 31, 2013
Assumptions used to calculate per-share fair value of stock option at the date of grant      
Expected life (in years)   6 years 28 days  
Risk-free interest rate, minimum (as a percent) 1.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum 1.71%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum 0.99%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum
Risk-free interest rate, maximum (as a percent) 2.04%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum 1.93%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum 1.52%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum
Expected volatility, minimum (as a percent) 58.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum 58.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum 56.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum
Expected volatility, maximum (as a percent) 59.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum 59.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum 57.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum
Expected dividend yield 0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate 0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate 0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
Minimum
     
Assumptions used to calculate per-share fair value of stock option at the date of grant      
Expected life (in years) 5 years 11 months 27 days   6 years 7 days
Maximum
     
Assumptions used to calculate per-share fair value of stock option at the date of grant      
Expected life (in years) 6 years 3 months 26 days   6 years 8 months 1 day