Income Taxes - Summary of Activity Related to Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Income Tax Disclosure [Abstract]
Unrecognized tax benefit—beginning of year	$ 3,304	$ 2,846
Gross increases —prior year tax positions	224	6	$ 1,351
Gross increases — current year tax positions	1,913	452	1,495
Unrecognized tax benefit—end of year	$ 5,441	$ 3,304	$ 2,846