Income Tax (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Income Tax Contingency [Line Items]
Effective tax rate, percent	20.00%	16.80%	15.50%	17.90%
Effective tax rate, excluding discrete items	19.10%	19.50%	19.60%	19.50%
Total Discrete tax benefit (expense), net	$ 22	$ 471	$ 1,190	$ 714