Accumulated Other Comprehensive Income - Component of Accumulated Other Comprehensive Income (loss) (Details) - USD ($) $ in Thousands	Jul. 31, 2020	Jan. 31, 2020	Jul. 31, 2019
Accumulated Other Comprehensive Income Loss [Line Items]
Foreign currency translation adjustments	$ 86,408	$ 85,345	$ 74,473
Available-for-sale securities	92	124	127
Total accumulated other comprehensive income	86,109	85,050	74,206
Unrecognized Prior Service Cost
Accumulated Other Comprehensive Income Loss [Line Items]
Defined benefit pension plan	(339)	(367)	(394)
Net Actuarial Loss
Accumulated Other Comprehensive Income Loss [Line Items]
Defined benefit pension plan	$ (52)	$ (52)	$ 0