Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity (Narratives) (Details)

v2.4.1.9
Stockholders' Equity (Narratives) (Details) (USD $)
In Millions, except Share data, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of shares available for grant 1,900,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant  
Weighted average grant date fair value (USD per share) $ 14.56us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue $ 9.81us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Share-based compensation expense $ 2.8us-gaap_AllocatedShareBasedCompensationExpense $ 1.8us-gaap_AllocatedShareBasedCompensationExpense
Unexercised Stock Options [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Vesting period 5 years  
Expiration period 10 years  
Restricted Stock [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Vesting period 3 years  
Unrecognized share-based compensation expense $ 15.4us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
 
Unvested restricted stock awards 2,100,000us-gaap_WeightedAverageNumberOfSharesRestrictedStock
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
 
Weighted average period for recognition of unvested shares 2 years 0 months 7 days  
Common Stock - Class A [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Number of shares authorized 15,700,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
/ us-gaap_StatementClassOfStockAxis
= us-gaap_CommonClassAMember