v3.8.0.1
Summary of Significant Accounting Policies - Summary of Assets and Liabilities Measured at Fair Value (Details) - USD ($)
$ in Thousands
Sep. 30, 2017
Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash and cash equivalents $ 345,380 $ 200,772
Available-for-sale securities 33 1,106
Total assets 345,413 201,878
Purchase consideration payable 4,994 4,994
Total liabilities 4,994 4,994
Recurring Measurements | Quoted Prices in Active Markets for Identical Items (Level 1)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash and cash equivalents 345,380 200,772
Available-for-sale securities 0 1,074
Total assets 345,380 201,846
Purchase consideration payable 0 0
Total liabilities 0 0
Recurring Measurements | Significant Other Observable Inputs (Level 2)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash and cash equivalents 0 0
Available-for-sale securities 0 0
Total assets 0 0
Purchase consideration payable 0 0
Total liabilities 0 0
Recurring Measurements | Significant Unobservable Inputs (Level 3)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash and cash equivalents 0 0
Available-for-sale securities 33 32
Total assets 33 32
Purchase consideration payable 4,994 4,994
Total liabilities $ 4,994 $ 4,994