Accumulated Other Comprehensive Income - Changes in AOCI (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Nov. 30, 2014		Nov. 30, 2013		Nov. 30, 2014		Nov. 30, 2013
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accumulated other comprehensive income balance at the beginning of the period	$ 224		$ 177		$ 85		$ 274
Other comprehensive gains (losses) before reclassifications, net of tax	326	[1]	(73)	[2]	452	[3]	(141)	[4]
Reclassifications to net income of previously deferred (gains) losses, net of tax	(25)	[5]	(14)	[6]	(12)	[7]	(43)	[8]
Other comprehensive income (loss)	301		(87)		440		(184)
Accumulated other comprehensive income balance at the end of the period	525		90		525		90
Other comprehensive income, before reclassification, tax benefit (expense)	(18)		9		(30)		7
Reclassification from accumulated other comprehensive income, tax (benefit) expense	1		(5)		4		(10)
Foreign Currency Translation Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accumulated other comprehensive income balance at the beginning of the period	11	[9]	10	[9]	9	[9]	41	[9]
Other comprehensive gains (losses) before reclassifications, net of tax	(34)	[1],[9]	14	[2],[9]	(32)	[3],[9]	(17)	[4],[9]
Reclassifications to net income of previously deferred (gains) losses, net of tax	0	[5],[9]	0	[6],[9]	0	[7],[9]	0	[8],[9]
Other comprehensive income (loss)	(34)	[9]	14	[9]	(32)	[9]	(17)	[9]
Accumulated other comprehensive income balance at the end of the period	(23)	[9]	24	[9]	(23)	[9]	24	[9]
Other comprehensive income, before reclassification, tax benefit (expense)	11		0		0		0
Reclassification from accumulated other comprehensive income, tax (benefit) expense	0		0		0		0
Cash Flow Hedges
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accumulated other comprehensive income balance at the beginning of the period	167		128		32		193
Other comprehensive gains (losses) before reclassifications, net of tax	351	[1]	(85)	[2]	470	[3]	(120)	[4]
Reclassifications to net income of previously deferred (gains) losses, net of tax	(18)	[5]	(15)	[6]	(2)	[7]	(45)	[8]
Other comprehensive income (loss)	333		(100)		468		(165)
Accumulated other comprehensive income balance at the end of the period	500		28		500		28
Other comprehensive income, before reclassification, tax benefit (expense)	(28)		9		(27)		7
Reclassification from accumulated other comprehensive income, tax (benefit) expense	3		(5)		7		(10)
Net Investment Hedges
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accumulated other comprehensive income balance at the beginning of the period	95	[9]	95	[9]	95	[9]	95	[9]
Other comprehensive gains (losses) before reclassifications, net of tax	0	[1],[9]	0	[3],[9]	0	[3],[9]	0	[4],[9]
Reclassifications to net income of previously deferred (gains) losses, net of tax	0	[5],[9]	0	[6],[9]	0	[7],[9]	0	[8],[9]
Other comprehensive income (loss)	0	[9]	0	[9]	0	[9]	0	[9]
Accumulated other comprehensive income balance at the end of the period	95	[9]	95	[9]	95	[9]	95	[9]
Other comprehensive income, before reclassification, tax benefit (expense)	0		0		0		0
Reclassification from accumulated other comprehensive income, tax (benefit) expense	0		0		0		0
Other
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accumulated other comprehensive income balance at the beginning of the period	(49)		(56)		(51)		(55)
Other comprehensive gains (losses) before reclassifications, net of tax	9	[1]	(2)	[2]	14	[3]	(4)	[4]
Reclassifications to net income of previously deferred (gains) losses, net of tax	(7)	[5]	1	[6]	(10)	[7]	2	[8]
Other comprehensive income (loss)	2		(1)		4		(2)
Accumulated other comprehensive income balance at the end of the period	(47)		(57)		(47)		(57)
Other comprehensive income, before reclassification, tax benefit (expense)	(1)		0		(3)		0
Reclassification from accumulated other comprehensive income, tax (benefit) expense	$ (2)		$ 0		$ (3)		$ 0

[1] Net of tax benefit (expense) of $11 million, $(28) million, $0 million, $(1) million and $(18) million, respectively.

[2] Net of tax benefit (expense) of $0 million, $9 million, $0 million, $0 million and $9 million, respectively.

[3] Net of tax benefit (expense) of $0 million, $(27) million, $0 million, $(3) million and $(30) million, respectively.

[4] Net of tax benefit (expense) of $0 million, $7 million, $0 million, $0 million and $7 million, respectively.

[5] Net of tax (benefit) expense of $0 million, $(3) million, $0 million, $2 million and $(1) million, respectively.

[6] Net of tax (benefit) expense of $0 million, $5 million, $0 million, $0 million and $5 million, respectively.

[7] Net of tax (benefit) expense of $0 million, $(7) million, $0 million, $3 million and $(4) million, respectively.

[8] Net of tax (benefit) expense of $0 million, $10 million, $0 million, $0 million and $10 million, respectively.

[9] The accumulated foreign currency translation adjustment and net investment hedge gains/losses related to an investment in a foreign subsidiary are reclassified to Net income upon sale or upon complete or substantially complete liquidation of the respective entity.