Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	COMMON STOCK	RETAINED EARNINGS	ACCUMULATED OTHER COMPREHENSIVE LOSS
Beginning Balance, Shares at Apr. 30, 2016		16,244,041
Beginning Balance at Apr. 30, 2016	$ 280,761	$ 163,290	$ 164,756	$ (47,285)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	53,851		53,851
Other comprehensive loss, net of tax	810			810
Stock-based compensation	2,477	$ 2,477
Exercise of stock-based compensation awards, net of amounts withheld for taxes, shares		122,522
Exercise of stock-based compensation awards, net of amounts withheld for taxes	626	$ 626
Stock repurchases, shares		(178,118)
Stock repurchases	(13,407)	$ (1,483)	(11,924)
Employee benefit plan contributions, shares		44,080
Employee benefit plan contributions	2,926	$ 2,926
Ending Balance, Shares at Jan. 31, 2017		16,232,525
Ending Balance at Jan. 31, 2017	$ 328,044	$ 167,836	206,683	(46,475)
Beginning Balance, Shares at Apr. 30, 2017	16,232,775	16,232,775
Beginning Balance at Apr. 30, 2017	$ 352,449	$ 168,835	224,031	(40,417)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	44,032		44,032
Other comprehensive loss, net of tax	750			750
Stock-based compensation	2,506	$ 2,506
Exercise of stock-based compensation awards, net of amounts withheld for taxes, shares		86,335
Exercise of stock-based compensation awards, net of amounts withheld for taxes	(1,494)	$ (1,494)
Stock issuance related to acquisition, shares		1,457,568
Stock issuance related to acquisition	189,849	$ 189,849
Stock repurchases, shares		(309,612)
Stock repurchases	(29,000)	$ (2,664)	(26,336)
Employee benefit plan contributions, shares		36,264
Employee benefit plan contributions	$ 3,554	$ 3,554
Ending Balance, Shares at Jan. 31, 2018	17,503,330	17,503,330
Ending Balance at Jan. 31, 2018	$ 562,646	$ 360,586	$ 241,727	$ (39,667)