Quarterly report pursuant to Section 13 or 15(d)

Cash, Cash Equivalents and Investments - Cash Equivalents and Investments (Details)

v3.10.0.1
Cash, Cash Equivalents and Investments - Cash Equivalents and Investments (Details)
$ in Thousands
 6 Months Ended
Jun. 30, 2018
USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Amortized Cost $ 100,316
Unrealized gains 982
Unrealized losses (199)
Fair Value 101,099
U.S. treasuries  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Amortized Cost 11,009
Unrealized gains 0
Unrealized losses (37)
Fair Value $ 10,972
U.S. treasuries | Minimum  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Contractual maturity 12 days
U.S. treasuries | Maximum  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Contractual maturity 159 days
Asset-backed securities  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Amortized Cost $ 10,640
Unrealized gains 12
Unrealized losses (30)
Fair Value $ 10,622
Asset-backed securities | Minimum  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Contractual maturity 16 days
Asset-backed securities | Maximum  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Contractual maturity 319 days
Asset-backed securities  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Amortized Cost $ 699
Unrealized gains 1
Unrealized losses 0
Fair Value $ 700
Asset-backed securities | Minimum  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Contractual maturity 365 days
Corporate bonds  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Amortized Cost $ 77,968
Unrealized gains 969
Unrealized losses (132)
Fair Value $ 78,805
Corporate bonds | Minimum  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Contractual maturity 3 days
Corporate bonds | Maximum  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Contractual maturity 299 days