Long-Term Debt - Additional Information (Detail)		9 Months Ended
	Feb. 28, 2017	Nov. 30, 2017 USD ($)
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Long-term debt		$ 30,000,000
Second Amendment [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Credit facility maturity date		Aug. 11, 2020
Revolving credit facility, maximum borrowing capacity		$ 100,000,000
Revolving credit facility, additional borrowing capacity		$ 50,000,000
Fixed charge coverage ratio, minimum		1.25
Line of credit facility, borrowing capacity description		(i) the Company’s net leverage ratio may not exceed 3.00:1.00, (ii) the Company’s fixed charge coverage ratio may not be less than 1.25:1.00, and (iii) the Company may make dividends or distributions to shareholders so long as (a) no event of default has occurred and is continuing and (b) the Company’s net leverage ratio both before and after giving effect to any such dividend or distribution is equal to or less than 2.50:1.00.
Revolving credit facility, interest rate description		LIBOR rate plus a spread ranging from 1.0% to 2.0%, which rate was 2.5% (3 month LIBOR + 1.0%) at November 30, 2017 and 1.86% (2 month LIBOR + 1.0%) at February 28, 2017.
Revolving credit facility, variable basis spread	1.00%	1.00%
Revolving credit facility, interest rate	1.86%	2.50%
Second Amendment [Member] | Revolving Credit Facility [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Net leverage ratio		3.00
Revolving credit facility, variable basis spread		2.00%
Second Amendment [Member] | Revolving Credit Facility [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Revolving credit facility, variable basis spread		1.00%
Second Amendment [Member] | Revolving Credit Facility [Member] | Dividends or Distributions Effect [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Net leverage ratio		2.50
Second Amendment [Member] | Letter of Credit [Member]
Line of Credit Facility [Line Items]
Long-term debt		$ 20,000,000
Second Amendment [Member] | Swing-line Loans [Member]
Line of Credit Facility [Line Items]
Long-term debt		15,000,000
Third Amendment [Member] | Standby Letters of Credit [Member]
Line of Credit Facility [Line Items]
Long-term debt		1,200,000
Revolving credit facility, remaining borrowing capacity		$ 68,800,000