Consolidated Statement Of Shareholders' Equity (Parenthetical) - $ / shares		3 Months Ended		12 Months Ended
	Feb. 20, 2018	Apr. 30, 2018	Apr. 30, 2017	Jan. 31, 2018
Statement of Stockholders' Equity [Abstract]
Dividends declared per common share	$ 2.08	$ 2.08	$ 2.04	$ 2.04