Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2017	Aug. 31, 2016
Operating Activities:
Net income	$ 596	$ 715
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	751	739
Provision for uncollectible accounts	60	39
Stock-based compensation	62	57
Deferred income taxes and other noncash items	97	173
Changes in assets and liabilities:
Receivables	(271)	20
Other assets	(142)	(4)
Accounts payable and other liabilities	(540)	(753)
Other, net	(23)	(15)
Cash provided by operating activities	590	971
Investing Activities:
Capital expenditures	(1,044)	(1,215)
Proceeds from asset dispositions and other	6	9
Cash used in investing activities	(1,038)	(1,206)
Financing Activities:
Principal payments on debt	(12)	(12)
Proceeds from stock issuances	150	40
Dividends paid	(134)	(106)
Purchase of treasury stock	(86)	(222)
Other, net	(6)	(13)
Cash used in financing activities	(88)	(313)
Effect of exchange rate changes on cash	70	3
Net decrease in cash and cash equivalents	(466)	(545)
Cash and cash equivalents at beginning of period	3,969	3,534
Cash and cash equivalents at end of period	$ 3,503	$ 2,989