XML 11 R41.htm IDEA: XBRL DOCUMENT v3.19.3
Investments - Summary of Amortized Cost, Gross Unrealized Gains and Losses, Fair Value and Level in Fair Value Hierarchy for Investments (Details) - USD ($)
$ in Thousands
Sep. 30, 2019
Dec. 31, 2018
Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents $ 88,337 $ 47,199
Level 1 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 88,337 47,199
Level 2 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 0 0
Short-term investments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Amortized Cost 185,243 175,736
Gross Unrealized Gains 387 0
Gross Unrealized (Losses) (8) (696)
Short-term investments | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 185,622 175,040
Short-term investments | Level 1 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 94,764 69,605
Short-term investments | Level 2 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 90,858 105,435
Short-term investments | U.S. government and agency bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Amortized Cost 106,135 112,995
Gross Unrealized Gains 204 0
Gross Unrealized (Losses) (7) (486)
Short-term investments | U.S. government and agency bonds | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 106,332 112,509
Short-term investments | U.S. government and agency bonds | Level 1 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 94,764 69,605
Short-term investments | U.S. government and agency bonds | Level 2 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 11,568 42,904
Short-term investments | Corporate bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Amortized Cost 71,329 56,235
Gross Unrealized Gains 156 0
Gross Unrealized (Losses) (1) (210)
Short-term investments | Corporate bonds | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 71,484 56,025
Short-term investments | Corporate bonds | Level 1 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 0 0
Short-term investments | Corporate bonds | Level 2 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 71,484 56,025
Short-term investments | Certificates of deposit    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Amortized Cost 7,779 6,506
Gross Unrealized Gains 27 0
Gross Unrealized (Losses) 0 0
Short-term investments | Certificates of deposit | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 7,806 6,506
Short-term investments | Certificates of deposit | Level 1 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 0 0
Short-term investments | Certificates of deposit | Level 2 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 7,806 6,506
Long-term investments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Amortized Cost 30,877 140,865
Gross Unrealized Gains 187 142
Gross Unrealized (Losses) (58) (223)
Long-term investments | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 31,006 140,784
Long-term investments | Level 1 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 9,979 64,086
Long-term investments | Level 2 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 21,027 76,698
Long-term investments | U.S. government and agency bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Amortized Cost 27,873 90,458
Gross Unrealized Gains 125 99
Gross Unrealized (Losses) (20) (155)
Long-term investments | U.S. government and agency bonds | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 27,978 90,402
Long-term investments | U.S. government and agency bonds | Level 1 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 9,979 64,086
Long-term investments | U.S. government and agency bonds | Level 2 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 17,999 26,316
Long-term investments | Corporate bonds    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Amortized Cost 814 46,743
Gross Unrealized Gains 44 43
Gross Unrealized (Losses) (38) (68)
Long-term investments | Corporate bonds | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 820 46,718
Long-term investments | Corporate bonds | Level 1 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 0 0
Long-term investments | Corporate bonds | Level 2 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 820 46,718
Long-term investments | Certificates of deposit    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Amortized Cost 2,190 3,664
Gross Unrealized Gains 18 0
Gross Unrealized (Losses) 0 0
Long-term investments | Certificates of deposit | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 2,208 3,664
Long-term investments | Certificates of deposit | Level 1 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 0 0
Long-term investments | Certificates of deposit | Level 2 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair Value 2,208 3,664
Money market mutual funds | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 83,342 47,199
Money market mutual funds | Level 1 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 83,342 47,199
Money market mutual funds | Level 2 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 0 $ 0
U.S. government and agency bonds | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 4,995  
U.S. government and agency bonds | Level 1 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 4,995  
U.S. government and agency bonds | Level 2 | Recurring fair value measurements    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents $ 0