Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jul. 31, 2017	Jan. 31, 2019	Jan. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 18,409	$ 1,996	$ 22,281	$ 61,664	$ 44,032
Other comprehensive income, net of tax:
Change in pension benefits, net of deferred taxes of $(105) and $(138), and $(315) and $(450) for the three and nine months ended January 31, 2019 and 2018, respectively	307		$ 262	921	750
Total Comprehensive Income	$ 18,716	$ 2,258		$ 62,585	$ 44,782