This item represents the deferred credit for an incentive or inducement received by a lessee from a lessor, in order to motivate the lessee to enter the lease agreement, which incentive or inducement is to be recognized as a reduction of rental expense over the lease term.

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The aggregate amount of payments due in the fifth year after the balance sheet date to reduce a recorded unconditional purchase obligation.

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Commitments and Contingencies (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	May 31, 2012	May 31, 2011	May 31, 2010
Aggregate amount of purchase obligations due in each of the next five fiscal years
2013	$ 250,458
2014	8,034
2015	412
2016	0
2017	0
Letters of credit and performance bonds outstanding	16,798
Facilities and Equipment
Commitments and Contingencies
Rent credits received from one of the facility lease agreements	239	34	47
Future minimum payments under operating leases
2013	28,155
2014	23,449
2015	18,789
2016	11,588
2017	9,423
2018 and thereafter	46,295
Rental expense
Rental expense, net	30,328	27,853	23,232
Aviation Equipment
Rental expense
Rental expense, net			$ 792