Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Tax [Line Items]
Effective Income Tax Rate Reconciliation, Percent	21.40%	6.80%	22.10%	11.70%
Provision for income taxes	$ 21,615	$ 5,545	$ 38,275	$ 14,503
TS
Tax [Line Items]
Deferred Other Tax Expense (Benefit)				$ (12,800)