Equity (Details Textual) - USD ($)			1 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended
	Mar. 15, 2016	Jan. 05, 2016	Oct. 31, 2015	Jul. 23, 2015	Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2016	Apr. 30, 2015	Jul. 31, 2015	Oct. 08, 2015
Equity (Textual)
Treasury stock, shares					42,000		42,000		42,000
Sale of treasury stock								$ 65,000
Stock-based compensation expense					$ 605,000	$ 295,000	$ 2,191,000	$ 1,524,000
Unrecognized compensation cost related to non-vested restricted shares					$ 2,851,000		2,851,000
2017							1,747,000
2018							825,000
2019							$ 279,000
Treasury Stock, Common [Member]
Equity (Textual)
Treasury stock, shares					41,723		41,723		41,723
Sale of treasury stock							$ 480,000		$ 480,000
Common Class B [Member]
Equity (Textual)
Exercise of stock options							1,452
Stock options cash received							$ 8,232
Common Class B [Member] | 2013 Plan [Member]
Equity (Textual)
Class B common stock available for the grant of awards										475,000
Common Class B [Member] | Restricted Shares [Member]
Equity (Textual)
Restricted shares, granted	8,000
Number of restricted shares issued, value	$ 285,000
Common Class B [Member] | Davidi Jonas [Member]
Equity (Textual)
Stock issued during period as compensation, Shares							60,000
Stock issued during period, Shares				60,000
Stock issued during period, Value				$ 1,495,000
Common Class B [Member] | Employee [Member]
Equity (Textual)
Stock issued during period as compensation, Shares							36,000
Common Class B [Member] | Employee [Member] | Restricted Shares [Member]
Equity (Textual)
Restricted shares, granted			28,000
Restricted shares, Vested			4,000
Number of restricted shares issued, value			$ 1,052,000
Description of restricted shares vesting condition			The balance of the shares will vest as to one-third of the granted shares on each of October 16, 2016, 2017 and 2018.
Common Class B [Member] | Employee [Member] | Restricted Shares [Member] | October 16, 2016 [Member]
Equity (Textual)
Restricted shares, Vested	4,000
Common Class B [Member] | Employee [Member] | Restricted Shares [Member] | March 16, 2017 [Member]
Equity (Textual)
Restricted shares, Vested	4,000
Common Class B [Member] | Directors [Member]
Equity (Textual)
Stock issued during period as compensation, Shares							24,000
Common Class B [Member] | Directors [Member] | Restricted Shares [Member]
Equity (Textual)
Restricted shares, granted		24,000
Number of restricted shares issued, value		$ 418,000
Common Class B [Member] | Consultant [Member]
Equity (Textual)
Stock issued during period as compensation, Shares							1,250