Investment Components, Including Associated Derivatives (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Jun. 30, 2017	Sep. 30, 2016	Jun. 30, 2016
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	$ 141,402	$ 136,160
Unrealized Gains	2,790	3,267
Unrealized Losses	(378)	(423)
Recorded Basis	143,814	139,004
Cash and cash equivalents	6,884	7,663	$ 13,928	$ 6,510
Short-term Investments	131,587	125,318
Equity and Other Investments	5,343	6,023
Cash
Cash, Cash Equivalents and Investments [Line Items]
Cash	4,052	3,624
Unrealized Gains	0	0
Unrealized Losses	0	0
Cash and cash equivalents	4,052	3,624
Short-term Investments	0	0
Equity and Other Investments	0	0
Mutual funds
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	1,040	1,478
Unrealized Gains	0	0
Unrealized Losses	0	0
Recorded Basis	1,040	1,478
Cash and cash equivalents	1,040	1,478
Short-term Investments	0	0
Equity and Other Investments	0	0
Commercial paper
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	833	319
Unrealized Gains	0	0
Unrealized Losses	0	0
Recorded Basis	833	319
Cash and cash equivalents	384	69
Short-term Investments	449	250
Equity and Other Investments	0	0
Certificates of deposit
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	1,430	1,358
Unrealized Gains	0	0
Unrealized Losses	0	0
Recorded Basis	1,430	1,358
Cash and cash equivalents	1,252	972
Short-term Investments	178	386
Equity and Other Investments	0	0
U.S. government and agency securities
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	117,222	112,119
Unrealized Gains	66	85
Unrealized Losses	(344)	(360)
Recorded Basis	116,944	111,844
Cash and cash equivalents	155	16
Short-term Investments	116,789	111,828
Equity and Other Investments	0	0
Foreign government bonds
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	5,150	5,276
Unrealized Gains	2	2
Unrealized Losses	(12)	(13)
Recorded Basis	5,140	5,265
Cash and cash equivalents	1	1,504
Short-term Investments	5,139	3,761
Equity and Other Investments	0	0
Mortgage- and asset-backed securities
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	3,771	3,921
Unrealized Gains	10	14
Unrealized Losses	(4)	(4)
Recorded Basis	3,777	3,931
Cash and cash equivalents	0	0
Short-term Investments	3,777	3,931
Equity and Other Investments	0	0
Corporate notes and bonds
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	4,872	4,786
Unrealized Gains	62	61
Unrealized Losses	(9)	(12)
Recorded Basis	4,925	4,835
Cash and cash equivalents	0	0
Short-term Investments	4,925	4,835
Equity and Other Investments	0	0
Municipal securities
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	284	284
Unrealized Gains	46	43
Unrealized Losses	0	0
Recorded Basis	330	327
Cash and cash equivalents	0	0
Short-term Investments	330	327
Equity and Other Investments	0	0
Common and preferred stock
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	2,220	2,472
Unrealized Gains	2,604	3,062
Unrealized Losses	(9)	(34)
Recorded Basis	4,815	5,500
Cash and cash equivalents	0	0
Short-term Investments	0	0
Equity and Other Investments	4,815	5,500
Other investments
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	528	523
Unrealized Gains	0	0
Unrealized Losses	0	0
Recorded Basis	528	523
Cash and cash equivalents	0	0
Short-term Investments	0	0
Equity and Other Investments	$ 528	$ 523