Shareholders' Equity (Narrative) (Details) $ in Millions	9 Months Ended
	Oct. 31, 2020 USD ($)
Retained Earnings Adjustments [Line Items]
Remaining share repurchase capacity	$ 707
Revolver [Member]
Retained Earnings Adjustments [Line Items]
Debt covenant leverage ratio	4
2018 Program [Member]
Retained Earnings Adjustments [Line Items]
Share repurchase authorization	$ 1,500