Condensed Consolidated Statements Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2015	Jan. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 7,282	$ 2,901	$ 24,191	$ 14,827
Other comprehensive income, net of tax:
Change in pension benefits, net of deferred tax of $(84) and $(110), and $(253) and $(330), for the three and nine months ended January 31, 2015 and 2014, respectively	132	172	395	517
Total Comprehensive Income	$ 7,414	$ 3,073	$ 24,586	$ 15,344