Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2015	Oct. 31, 2014	Oct. 31, 2015	Oct. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 18,180	$ 7,671	$ 33,338	$ 16,909
Other comprehensive income, net of tax:
Change in pension benefits, net of deferred tax benefit of $(138) and $(84), and $(275) and $(167), for the three and six months ended October 31, 2015 and 2014, respectively	216	132	431	263
Total Comprehensive Income	$ 18,396	$ 7,803	$ 33,769	$ 17,172