Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Feb. 28, 2017	Feb. 29, 2016
Operating Activities:
Net income	$ 1,977	$ 1,890
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	2,241	1,964
Provision for uncollectible accounts	115	90
Stock-based compensation	123	115
Deferred income taxes and other noncash items	474	288
Gain from sale of investment	(35)
Changes in assets and liabilities:
Receivables	(340)	(78)
Other assets	(235)	(322)
Accounts payable and other liabilities	(1,642)	(146)
Other, net	(33)	(5)
Cash provided by operating activities	2,645	3,796
Investing Activities:
Capital expenditures	(3,790)	(3,562)
Proceeds from asset dispositions and other	123	(17)
Cash used in investing activities	(3,667)	(3,579)
Financing Activities:
Principal payments on debt	(49)	(28)
Proceeds from debt issuances	1,190	1,238
Proceeds from stock issuances	265	79
Dividends paid	(319)	(210)
Purchase of treasury stock	(358)	(2,133)
Other, net	2	(7)
Cash provided by (used in) financing activities	731	(1,061)
Effect of exchange rate changes on cash	(70)	(78)
Net decrease in cash and cash equivalents	(361)	(922)
Cash and cash equivalents at beginning of period	3,534	3,763
Cash and cash equivalents at end of period	$ 3,173	$ 2,841