Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Nov. 30, 2015	Nov. 30, 2014
Operating Activities:
Net income	$ 1,383	$ 1,316
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	1,301	1,302
Provision for uncollectible accounts	57	78
Stock-based compensation	86	79
Deferred income taxes and other noncash items	(48)	(37)
Changes in assets and liabilities:
Receivables	(263)	(317)
Other assets	(113)	(46)
Accounts payable and other liabilities	66	(201)
Other, net	(15)	(23)
Cash provided by operating activities	2,454	2,151
Investing Activities:
Capital expenditures	(2,562)	(1,890)
Proceeds from asset dispositions and other	12	7
Cash used in investing activities	(2,550)	(1,883)
Financing Activities:
Principal payments on debt	(17)	(1)
Proceeds from debt issuances	1,238
Proceeds from stock issuances	62	189
Excess tax benefit on the exercise of stock options	8	23
Dividends paid	(141)	(114)
Purchase of treasury stock	(1,101)	(947)
Other, net	(16)
Cash provided by (used in) financing activities	33	(850)
Effect of exchange rate changes on cash	(53)	(60)
Net decrease in cash and cash equivalents	(116)	(642)
Cash and cash equivalents at beginning of period	3,763	2,908
Cash and cash equivalents at end of period	$ 3,647	$ 2,266