Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	May 31, 2016	May 31, 2015	May 31, 2014
Operating Activities:
Net income	$ 1,820	$ 1,050	$ 2,324
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	2,631	2,611	2,587
Provision for uncollectible accounts	121	145	130
Deferred income taxes and other noncash items	31	(572)	339
Impairment and other charges		246
Stock-based compensation	144	133	117
Retirement plans mark-to-market adjustment	1,498	2,190	15
Changes in assets and liabilities:
Receivables	(199)	(392)	(516)
Other current assets	(234)	25	(22)
Pension and postretirement healthcare assets and liabilities, net	(346)	(692)	(453)
Accounts payable and other liabilities	467	659	(235)
Other, net	(225)	(37)	(22)
Cash provided by operating activities	5,708	5,366	4,264
Investing Activities:
Capital expenditures	(4,818)	(4,347)	(3,533)
Business acquisitions, net of cash acquired	(4,618)	(1,429)	(36)
Proceeds from asset dispositions and other	(10)	24	18
Cash used in investing activities	(9,446)	(5,752)	(3,551)
Financing Activities:
Principal payments on debt	(41)	(5)	(254)
Proceeds from debt issuance	6,519	2,491	1,997
Proceeds from stock issuances	183	320	557
Excess tax benefit on the exercise of stock options	3	51	44
Dividends paid	(277)	(227)	(187)
Purchase of treasury stock	(2,722)	(1,254)	(4,857)
Other, net	(54)	(27)	(19)
Cash provided by (used in) financing activities	3,611	1,349	(2,719)
Effect of exchange rate changes on cash	(102)	(108)	(3)
Net (decrease) increase in cash and cash equivalents	(229)	855	(2,009)
Cash and cash equivalents at beginning of period	3,763	2,908	4,917
Cash and cash equivalents at end of period	$ 3,534	$ 3,763	$ 2,908