XML 68 R41.htm IDEA: XBRL DOCUMENT v3.19.1
Investments (Details)
$ in Thousands
12 Months Ended
Dec. 31, 2018
USD ($)
security
Dec. 31, 2017
USD ($)
security
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost $ 634 $ 21,946
Unrealized Gain 0 0
Unrealized Loss 0 (2)
Fair Value $ 634 $ 21,944
Short-term investments    
Debt Securities, Available-for-sale [Line Items]    
Weighted average maturity of short-term investments 1 month 2 months 12 days
Debt securities    
Debt Securities, Available-for-sale [Line Items]    
Fair value of security in unrealized loss position for less than twelve months   $ 1,500
Corporate commercial paper, stock, bonds and notes | Short-term investments    
Debt Securities, Available-for-sale [Line Items]    
Amortized Cost $ 634 21,946
Unrealized Gain 0 0
Unrealized Loss 0 (2)
Fair Value $ 634 $ 21,944
Debt securities    
Debt Securities, Available-for-sale [Line Items]    
Number of securities in unrealized loss position for less than 12 months | security 0 1
Number of securities in unrealized loss position for more than 12 months | security 0 0
Minimum | Short-term investments    
Debt Securities, Available-for-sale [Line Items]    
Range of maturities 1 month 1 month
Maximum | Short-term investments    
Debt Securities, Available-for-sale [Line Items]    
Range of maturities 12 months 12 months