Derivative Financial Instruments (Details 2) (USD $) In Thousands, unless otherwise specified	Aug. 31, 2013 item	May 31, 2013
Derivative Financial Instruments
Number of parties in transaction	2
Assets:
Net amounts of assets presented in the condensed consolidated balance sheets	$ 298,472	$ 257,878
Liabilities:
Net amounts of liabilities presented in the condensed consolidated balance sheets	392,952	475,278
Interest rate swaps
Assets:
Gross amounts of recognized assets	298,472	257,878
Net amounts of assets presented in the condensed consolidated balance sheets	298,472	257,878
Gross amounts not offset in the condensed consolidated balance sheets - Financial instruments	218,912	203,161
Net amount	79,560	54,717
Liabilities:
Gross amounts of recognized liabilities	392,952	475,278
Net amounts of liabilities presented in the condensed consolidated balance sheets	392,952	475,278
Gross amounts not offset in the condensed consolidated balance sheets - Financial instruments	218,912	203,161
Net amount	$ 174,040	$ 272,117

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Fair value of liability associated with derivative asset, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

+ References

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Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

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Fair value of derivative asset, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

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The amount as of the balance sheet date of the fair value of derivative assets that in accordance with the entity's accounting policy was not offset against an obligation to return cash collateral under a master netting arrangement.

+ References

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Fair value of derivative liability, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

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The amount as of the balance sheet date of the fair value of derivative liabilities that in accordance with the entity's accounting policy was not offset against the right to reclaim cash collateral under a master netting arrangement.

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Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, net of the effects of master netting arrangements.

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