Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability	$ 18,800	$ 17,200	$ 15,700
Contingent consideration liability	18,800	17,200	$ 15,700
Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability	18,800	17,200
Money market funds	62,855	112,808
Liability, total	18,800	17,200
Asset, total	62,855	112,808
Contingent consideration liability	18,800	17,200
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability	0	0
Money market funds	62,855	112,808
Liability, total	0	0
Asset, total	62,855	112,808
Contingent consideration liability	0	0
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability	0	0
Money market funds	0	0
Liability, total	0	0
Asset, total	0	0
Contingent consideration liability	0	0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration liability	18,800	17,200
Money market funds	0	0
Liability, total	18,800	17,200
Asset, total	0	0
Contingent consideration liability	$ 18,800	$ 17,200