Note 11 - Stockholders' Equity - Consolidated Statements of Changes in Stockholders' Equity (Details)	9 Months Ended
	Feb. 28, 2016 USD ($) shares
Employee Stock Option [Member]
Common Stock Shares
Stock options exercised, net of shares tendered (in shares) | shares	72,673
Stock options exercised, net of shares tendered	$ 0
Additional Paid-in Capital
Stock options exercised, net of shares tendered	282,000
Stock Swaps and RSUs [Member]
Additional Paid-in Capital
Taxes paid by Company for stock swaps and RSUs	$ 0
Balance (in shares) | shares	26,990,490	[1]
Vested restricted stock units, net of shares tendered (in shares) | shares	8,114
Balance (in shares) | shares	27,071,277
Balance	$ 27,000	[2]
Vested restricted stock units, net of shares tendered	0
Balance	27,000
Balance	133,307,000	[2]
Vested restricted stock units, net of shares tendered	0
Stock-based compensation expense	2,581,000
Tax benefit from stock based compensation expense	133,000
Balance	136,303,000
Retained Earnings
Balance	85,098,000	[2]
Net loss applicable to common stockholders	(16,370,000)
Balance	68,728,000
Non-controlling Interest
Balance	1,677,000	[2]
Non-controlling interest in net income	119,000
Distributions to non-controlling interest	(248,000)
Balance	$ 1,548,000

[1] Derived from audited financial statements.

[2] Derived from audited financial statements.