XML 42 R27.htm IDEA: XBRL DOCUMENT v3.8.0.1
Cash, Cash Equivalents And Investments (Summary Of Cash, Cash Equivalents And Investments) (Details) - USD ($)
$ in Thousands
Sep. 30, 2017
Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]    
Amortized cost $ 83,967 $ 71,973
Gross unrealized gains 3 13
Gross unrealized losses (5) (8)
Fair value 83,965 71,978
Cash and cash equivalents [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized cost 25,931 16,765
Gross unrealized gains
Gross unrealized losses
Fair value 25,931 16,765
Investments [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized cost 58,036 55,208
Gross unrealized gains 3 13
Gross unrealized losses (5) (8)
Fair value 58,034 55,213
Cash and money market funds [Member] | Cash and cash equivalents [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized cost 22,283 14,516
Gross unrealized gains
Gross unrealized losses
Fair value 22,283 14,516
Commercial paper [Member] | Cash and cash equivalents [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized cost 3,648 2,249
Gross unrealized gains
Gross unrealized losses
Fair value 3,648 2,249
Commercial paper [Member] | Investments [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized cost 23,881 23,581
Gross unrealized gains 2 5
Gross unrealized losses (1) (3)
Fair value 23,882 23,583
Corporate debt securities [Member] | Investments [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized cost 9,399 10,741
Gross unrealized gains 1 1
Gross unrealized losses (1) (3)
Fair value 9,399 10,739
Asset backed securities [Member] | Investments [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized cost   312
Gross unrealized gains  
Gross unrealized losses  
Fair value   312
U.S. government and agency securities [Member] | Investments [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized cost 24,756 20,574
Gross unrealized gains 7
Gross unrealized losses (3) (2)
Fair value 24,753 20,579
Cash [Member] | Long-term restricted cash [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized cost 4,500 4,500
Gross unrealized gains
Gross unrealized losses
Fair value $ 4,500 $ 4,500