Annual report pursuant to Section 13 and 15(d)

Stock Incentive Plan - Fair Value Assumptions (Details)

v2.4.1.9
Stock Incentive Plan - Fair Value Assumptions (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Fair value significant assumptions:      
Future dividends $ 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments $ 0.00us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments $ 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendPayments
Stock Options      
Fair value significant assumptions:      
Risk-free interest rate, minimum 1.93%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
1.03%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
0.82%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
Risk-free interest rate, maximum 2.01%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
2.18%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
1.25%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
Expected volatility, minimum 50.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
34.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
32.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
Expected volatility, maximum 52.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
52.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
 
Expected life 6 years 6 months   6 years 6 months
Cliff vesting period 1 year    
Ratable vesting period 5 years    
Options ratable vesting frequency 1 year    
Stock Options | Minimum      
Fair value significant assumptions:      
Expected life   6 years  
Stock Options | Maximum      
Fair value significant assumptions:      
Expected life   6 years 6 months