Taxes (Schedule of Income Tax Rate) (Details)	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Taxes [Abstract]
U.S. statutory tax rate	33.80%	35.00%	35.00%
U.S. state income taxes, net of federal income tax benefit	1.80%	1.70%	1.80%
Transition tax on accumulated foreign earnings	12.30%	0.00%	0.00%
Deferred tax benefit from change in tax rate	(14.10%)	0.00%	0.00%
Income taxed outside the U.S.	(4.10%)	(4.50%)	(4.00%)
Net impact of repatriated international earnings	(0.10%)	(1.00%)	0.10%
Other, net	0.80%	(0.90%)	(2.60%)
Effective income tax rate	30.40%	30.30%	30.30%