Segment Data - Additional Information (Detail)	12 Months Ended
	May 31, 2014 Segment
Segment Reporting Information [Line Items]
Number of reportable segments	3
Joint Venture Transactions | PSI Energy Solutions, LLC
Segment Reporting Information [Line Items]
Percent of controlling interest by the company	75.00%
Joint Venture Transactions | Professional Supply, Inc.
Segment Reporting Information [Line Items]
Percent of controlling interest by the company	20.00%
Joint Venture Transactions | Stonehenge Structured Finance Partners, LLC
Segment Reporting Information [Line Items]
Percent of controlling interest by the company	5.00%