Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements (Details)

v3.7.0.1
Fair Value Measurements (Details) - Recurring [Member] - USD ($)
$ in Thousands
Jun. 30, 2017
Dec. 31, 2016
Financial assets measured at fair value on a recurring basis [Abstract]    
Cash and cash equivalents $ 110,343 $ 106,932
Available-for-sale debt securities 0 1,511
Total 110,343 108,443
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]    
Financial assets measured at fair value on a recurring basis [Abstract]    
Cash and cash equivalents 110,343 106,932
Available-for-sale debt securities 0 0
Total 110,343 106,932
Significant Other Observable Inputs (Level 2) [Member]    
Financial assets measured at fair value on a recurring basis [Abstract]    
Cash and cash equivalents 0 0
Available-for-sale debt securities 0 1,511
Total 0 1,511
Significant Unobservable Inputs (Level 3) [Member]    
Financial assets measured at fair value on a recurring basis [Abstract]    
Cash and cash equivalents 0 0
Available-for-sale debt securities 0 0
Total $ 0 $ 0