Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 18,488	$ 19,755	$ 22,281	$ 43,255	$ 42,036
Other comprehensive income, net of tax:
Change in pension benefits, net of deferred taxes of $(105) and $(156), and $(210) and $(312) for the three and six months ended October 31, 2018 and 2017, respectively	307		$ 244	614	488
Total Comprehensive Income	$ 18,795	$ 19,999		$ 43,869	$ 42,524