Accumulated Other Comprehensive Income - Changes in AOCI (Detail) - USD ($) $ in Millions	3 Months Ended						6 Months Ended
	Nov. 30, 2015		Aug. 31, 2015		Nov. 30, 2014		Nov. 30, 2015		Nov. 30, 2014		May. 31, 2015	Aug. 31, 2014	May. 31, 2014
AOCI Including Portion Attributable to Noncontrolling, net of Tax [Roll Forward]
Accumulated other comprehensive income balance at the beginning of the period	$ 833		$ 1,246		$ 224		$ 1,246		$ 85
Other comprehensive gains (losses) before reclassifications, net of tax	407	[1]			326	[2]	184	[3]	452	[4]
Reclassifications to net income of previously deferred (gains) losses, net of tax	(133)	[5]			(25)	[6]	(323)	[7]	(12)	[8]
Total other comprehensive income (loss), net of tax	274				301		(139)		440
Accumulated other comprehensive income balance at the end of the period	1,107		833		525		1,107		525
Other comprehensive income, before reclassification, tax benefit (expense)	16				(18)		14		(30)
Reclassification from accumulated other comprehensive income, tax (benefit) expense	0				(1)		1		(4)
Foreign Currency Translation Adjustment
AOCI Including Portion Attributable to Noncontrolling, net of Tax [Roll Forward]
Accumulated other comprehensive income balance at the beginning of the period	(112)	[9],[10]	(31)	[11],[12]	(9)	[13],[14]	(31)	[11],[12]	(11)	[15],[16]
Other comprehensive gains (losses) before reclassifications, net of tax	(29)	[1],[9],[10]			(34)	[2],[13],[14]	(110)	[3],[11],[12]	(32)	[4],[15],[16]
Reclassifications to net income of previously deferred (gains) losses, net of tax	0	[5],[9],[10]			0	[6],[13],[14]	0	[7],[11],[12]	0	[8],[15],[16]
Total other comprehensive income (loss), net of tax	(29)	[9],[10]			(34)	[13],[14]	(110)	[11],[12]	(32)	[15],[16]
Accumulated other comprehensive income balance at the end of the period	(141)	[9],[10],[11],[12]	(112)	[9],[10]	(43)	[13],[14],[15],[16]	(141)	[9],[10],[11],[12]	(43)	[13],[14],[15],[16]
Other comprehensive income, before reclassification, tax benefit (expense)	0				11		0		0
Reclassification from accumulated other comprehensive income, tax (benefit) expense	0				0		0		0
Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling, net of Tax [Roll Forward]
Accumulated other comprehensive income balance at the beginning of the period	891		1,220	[17]	167		1,220	[17]	32
Other comprehensive gains (losses) before reclassifications, net of tax	425	[1]			351	[2]	283	[3],[17]	470	[4]
Reclassifications to net income of previously deferred (gains) losses, net of tax	(135)	[5]			(18)	[6]	(322)	[7],[17]	(2)	[8]
Total other comprehensive income (loss), net of tax	290				333		(39)	[17]	468
Accumulated other comprehensive income balance at the end of the period	1,181	[17]	891		500		1,181	[17]	500
Other comprehensive income, before reclassification, tax benefit (expense)	18				(28)		16		(27)
Reclassification from accumulated other comprehensive income, tax (benefit) expense	0				(3)		1		(7)
Net Investment Hedges
AOCI Including Portion Attributable to Noncontrolling, net of Tax [Roll Forward]
Accumulated other comprehensive income balance at the beginning of the period	115	[9],[10]	115	[11],[12]	115	[13],[14]	115	[11],[12]	115	[15],[16]
Other comprehensive gains (losses) before reclassifications, net of tax	0	[1],[9],[10]			0	[2],[13],[14]	0	[3],[11],[12]	0	[4],[15],[16]
Reclassifications to net income of previously deferred (gains) losses, net of tax	0	[5],[9],[10]			0	[6],[13],[14]	0	[7],[11],[12]	0	[8],[15],[16]
Total other comprehensive income (loss), net of tax	0	[9],[10]			0	[13],[14]	0	[11],[12]	0	[15],[16]
Accumulated other comprehensive income balance at the end of the period	115	[9],[10],[11],[12]	115	[9],[10]	115	[13],[14],[15],[16]	115	[9],[10],[11],[12]	115	[13],[14],[15],[16]
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
AOCI Including Portion Attributable to Noncontrolling, net of Tax [Roll Forward]
Accumulated other comprehensive income balance at the beginning of the period	(61)		(58)		(49)		(58)		(51)
Other comprehensive gains (losses) before reclassifications, net of tax	11	[1]			9	[2]	11	[3]	14	[4]
Reclassifications to net income of previously deferred (gains) losses, net of tax	2	[5]			(7)	[6]	(1)	[7]	(10)	[8]
Total other comprehensive income (loss), net of tax	13				2		10		4
Accumulated other comprehensive income balance at the end of the period	(48)		(61)		(47)		(48)		(47)
Other comprehensive income, before reclassification, tax benefit (expense)	(2)				(1)		(2)		(3)
Reclassification from accumulated other comprehensive income, tax (benefit) expense	0				2		0		3
Revisions
AOCI Including Portion Attributable to Noncontrolling, net of Tax [Roll Forward]
Accumulated other comprehensive income balance at the beginning of the period	$ 20		20		$ 20		$ 20		$ 20
Accumulated other comprehensive income balance at the end of the period			20
Amount of Gain (Loss) Recognized in Other Comprehensive Income on Derivatives			40
Translation adjustment for net investment hedge			$ 20								$ 20	$ 20	$ 20

[1] Net of tax benefit (expense) of $0 million, $18 million, $0 million, $(2) million and $16 million, respectively.

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

[3] Net of tax benefit (expense) of $0 million, $16 million, $0 million, $(2) million and $14 million, respectively.

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

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

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

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

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

[9] Beginning balances have been updated to reflect the proper classification of $20 million of deferred tax balances between Foreign Currency Translation Adjustment and Net Investment Hedges.

[10] 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.

[11] Beginning balances have been updated to reflect the proper classification of $20 million of deferred tax balances between Foreign Currency Translation Adjustment and Net Investment Hedges.

[12] 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.

[13] Beginning and ending balances have been updated to reflect the proper classification of $20 million of deferred tax balances between Foreign Currency Translation Adjustment and Net Investment Hedges.

[14] 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.

[15] Beginning and ending balances have been updated to reflect the proper classification of $20 million of deferred tax balances between Foreign Currency Translation Adjustment and Net Investment Hedges.

[16] 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.

[17] Certain amounts have been updated to reflect the proper classification of $40 million between Other comprehensive gains (losses) before reclassifications and Reclassifications to net income of previously deferred (gains) losses for the three months ended August 31, 2015.