Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	May 31, 2017	May 31, 2016	May 31, 2015
OPERATING ACTIVITIES
Net income	$ 2,997	$ 1,820	$ 1,050
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	2,995	2,631	2,611
Provision for uncollectible accounts	136	121	145
Deferred income taxes and other noncash items	909	31	(572)
Stock-based compensation	154	144	133
Retirement plans mark-to-market adjustment	(24)	1,498	2,190
Gain from sale of investment	(35)
Impairment and other charges			246
Changes in assets and liabilities:
Receivables	(556)	(199)	(392)
Other current assets	78	(234)	25
Pension and postretirement healthcare assets and liabilities, net	(1,688)	(346)	(692)
Accounts payable and other liabilities	103	467	659
Other, net	(139)	(225)	(37)
Cash provided by operating activities	4,930	5,708	5,366
INVESTING ACTIVITIES
Capital expenditures	(5,116)	(4,818)	(4,347)
Business acquisitions, net of cash acquired		(4,618)	(1,429)
Proceeds from asset dispositions and other	135	(10)	24
Cash used in investing activities	(4,981)	(9,446)	(5,752)
FINANCING ACTIVITIES
Principal payments on debt	(82)	(41)	(5)
Proceeds from debt issuances	1,190	6,519	2,491
Proceeds from stock issuances	337	183	320
Dividends paid	(426)	(277)	(227)
Purchase of treasury stock	(509)	(2,722)	(1,254)
Other, net	18	(51)	24
Cash provided by financing activities	528	3,611	1,349
Effect of exchange rate changes on cash	(42)	(102)	(108)
Net increase (decrease) in cash and cash equivalents	435	(229)	855
Cash and cash equivalents at beginning of period	3,534	3,763	2,908
Cash and cash equivalents at end of period	$ 3,969	$ 3,534	$ 3,763