Condensed Consolidated Statements of Shareholders' Equity (UNAUDITED) (Parenthetical) - $ / shares shares in Thousands	3 Months Ended
	Jul. 31, 2020	Apr. 30, 2020	Jan. 31, 2020	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019
Statement Of Stockholders Equity [Abstract]
Purchase of treasury shares, shares	53,735	300,894	26,223	261	78,957	901,545
Dividends declared per share	$ 0.38	$ 0.38	$ 0.38	$ 0.35	$ 0.35	$ 0.35