Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2018	Jul. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 24,767	$ 22,281
Other comprehensive income, net of tax:
Change in pension benefits, net of deferred taxes of $(105) and $(156), for the three months ended July 31, 2018 and 2017, respectively	307	244
Total Comprehensive Income	$ 25,074	$ 22,525