Restructuring and Impairment Charges (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended		3 Months Ended	12 Months Ended
	May 31, 2011 item	May 31, 2012	May 31, 2011	May 31, 2012 Structures and Systems segment item	May 31, 2012 Structures and Systems segment
Restructuring and Impairment Charges
Number of plants which will be closed				2
Number of idle facilities which will be closed				1
Impairment charges	$ 5,355				$ 2,500
Assets impairment charges		3,700	5,355		3,700
Severance expense					1,200
Number of narrow body aircraft offered for sale	1
Net realizable value	$ 8,850		$ 8,850