Short-term Investments (Details) $ in Thousands	Mar. 31, 2017 USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 34,991
Unrealized Gains	35
Unrealized Losses	70
Fair Value	34,956
Held-to-maturity investments with contractual maturities less than one year	35,000
U.S. government securities
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	34,991
Unrealized Gains	35
Unrealized Losses	70
Fair Value	$ 34,956