Fair Value Measurement - Rollforward for Liabilities Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]  
Payments $ (699)
Business Combination Accrued Contingent Consideration [Member]  
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]  
Beginning balance 44,911
Addition through acquisition transactions 8,039
Adjustment for prior year transactions (283)
Change in accrued contingent consideration 4,379
Payments (738)
Ending balance $ 56,308