Income Taxes - Components of Income Tax Expense/(Benefit) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Feb. 28, 2014	Feb. 28, 2013	Feb. 28, 2014	Feb. 28, 2013
Income Tax Disclosure [Abstract]
Income tax expense/(benefit) based on income/(loss) from continuing operations at estimated tax rates of 45.7% in 2014 and 70.3% in 2013	$ 2,555	$ (1,280)	$ 2,217	$ 110
Discrete tax expense/(benefit):
Non taxable gain on revaluation of contingent consideration liability at estimated tax rate of 45.7% in 2014	(2,285)		(2,285)
Adjustment for elimination of the ASC 718 APIC pool	57		123
Provision for change in projected tax rates	(50)	601
Retroactive renewal of research and experimentation credit		(129)		(129)
Adjustments to prior period tax liabilities	156	(30)	170	(3)
Non deductible acquisition costs		9		102
Adjustment to fully reserved capital losses	43		43	(179)
Total income tax expense/(benefit)	$ 476	$ (829)	$ 268	$ (99)