Cash Equivalents and Short-term Investments - Schedule of Contractual Maturities of Short-term Investments (Details) - USD ($) $ in Thousands	Apr. 30, 2017	Jan. 31, 2017
Amortized Cost
Amortized cost, due within one year	$ 2,500	$ 12,842
Amortized cost, due between one to five years	0	1,538
Investments, amortized cost	2,500	14,380
Estimated Fair Value
Estimated fair value, due within one year	2,500	12,852
Estimated fair value, due between one to five years	0	1,538
Estimated fair value total	$ 2,500	$ 14,390