Stock Repurchase Program (Details) - Common Stock Repurchase Program - $ / shares shares in Millions	12 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2019
Class of Stock [Line Items]
Repurchase and retirement of common shares (in shares)	2.6	2.7	2.2
Average repurchase price per share (in dollars per share)	$ 207.61	$ 168.63	$ 130.15
Common stock shares remained available for repurchase under repurchase plans (in shares)	12.1