Quarterly report pursuant to Section 13 or 15(d)

Cash, Cash Equivalents, and Short-Term Investments (Details 1)

v3.7.0.1
Cash, Cash Equivalents, and Short-Term Investments (Details 1) - USD ($)
$ in Thousands
Jun. 30, 2017
Dec. 31, 2016
Jun. 30, 2016
Dec. 31, 2015
Cash and Cash Equivalents [Line Items]        
Cash $ 80,303 $ 213,551 $ 96,284 $ 82,469
Schedule of Available-for-sale Securities [Line Items]        
Short-term investments 0 34,019    
Total cash, cash equivalents and short-term investments 80,303 247,570    
US Investment Grade Bonds [Member]        
Schedule of Available-for-sale Securities [Line Items]        
Short-term investments 0 24,477    
Developed Investment Grade Bonds [Member]        
Schedule of Available-for-sale Securities [Line Items]        
Short-term investments 0 9,542    
Cash [Member]        
Cash and Cash Equivalents [Line Items]        
Cash $ 80,303 $ 213,551