Risk Management and Derivatives - Additional Information (Detail) - USD ($)	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Ineffectiveness for cash flow hedges		$ 0	$ 0
Deferred net gains (net of tax) on both outstanding and matured derivatives accumulated in other comprehensive income are expected to be reclassified to net income during the next twelve months as a result of underlying hedged transactions also being recorded in net income	$ 96,000,000
Maximum term over which the Company is hedging exposures to the variability of cash flows for its forecasted and recorded transactions (in months)	24 months
Fair value hedge ineffectiveness		0	0
Ineffectiveness on net investment hedges	$ 0	0	$ 0
Derivative, net liability position, aggregate fair value	0
Collateral received from counterparties to hedging instruments	23,000,000	0
Not designated as derivative instrument
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total notional amount of outstanding derivatives	6,100,000,000
Embedded derivatives
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total notional amount of outstanding derivatives	260,000,000
Minimum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Minimum fair value of outstanding derivative above which the credit related contingent features require the derivative party to post collateral	$ 50,000,000
Derivatives designated as cash flow hedges
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Additional period for forecasted transaction expected to occur	2 months
Percentage of anticipated exposures hedged (percent)	100.00%
Total notional amount of outstanding derivatives	$ 12,200,000,000
Derivatives designated as cash flow hedges | Minimum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Typical time period that anticipated exposures are hedged against (in months)	12 months
Derivatives designated as cash flow hedges | Maximum
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Typical time period that anticipated exposures are hedged against (in months)	24 months
Derivatives designated as fair value hedges | Interest rate swaps
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Total notional amount of outstanding derivatives	$ 0
Fair value hedge ineffectiveness	0
Derivatives designated as net investment hedges | Foreign Exchange Contract
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative assets (liabilities), at fair value, net	0
Cash and Cash Equivalents
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Collateral received from counterparties to hedging instruments	23,000,000
Cash and Cash Equivalents | Foreign Exchange Contract
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Collateral received from counterparties to hedging instruments	$ 23,000,000	$ 0