Stockholders' Equity Dividends (Details) - $ / shares	3 Months Ended
	Jul. 31, 2017	Jul. 31, 2016
Class of Stock [Line Items]
Common Stock, Dividends, Per Share, Declared	$ 0.365	$ 0.34
July 2017 dividend payment [Member]
Class of Stock [Line Items]
Dividends Payable, Date Declared, Month and Year	May 24, 2017
Dividends Payable, Date of Record	Jun. 05, 2017
Dividends Payable, Date to be Paid	Jul. 03, 2017
Common Stock, Dividends, Per Share, Declared	$ 0.1825
October 2017 dividend payment [Member]
Class of Stock [Line Items]
Dividends Payable, Date Declared, Month and Year	Jul. 27, 2017
Dividends Payable, Date of Record	Sep. 07, 2017
Dividends Payable, Date to be Paid	Oct. 02, 2017
Common Stock, Dividends, Per Share, Declared	$ 0.1825