Investment Components (Detail) - USD ($) $ in Millions		Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2017	Jun. 30, 2017
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		$ 133,105
Debt investments, Recorded Basis		131,651
Derivative, net		290	$ 386
Cash and cash equivalents		15,137	11,946	$ 6,884	$ 7,663
Short-term Investments		120,743	121,822
Equity Investments		2,034	1,862
Cash, cash equivalents, and investments		137,914	135,630
Equity investments
Cash, Cash Equivalents and Investments [Line Items]
Equity investments, Recorded Basis		2,273	2,109
Cash and cash equivalents		239	246
Short-term Investments		0	1
Equity Investments		2,034	1,862
Equity investments | Other
Cash, Cash Equivalents and Investments [Line Items]
Equity investments, Recorded Basis		1,711	1,558
Cash and cash equivalents		0	0
Short-term Investments		0	1
Equity Investments		1,711	1,557
Equity investments | Level 1
Cash, Cash Equivalents and Investments [Line Items]
Equity investments, Recorded Basis		562	533
Cash and cash equivalents		239	246
Short-term Investments		0	0
Equity Investments		323	287
Equity investments | Level 3
Cash, Cash Equivalents and Investments [Line Items]
Equity investments, Recorded Basis			18
Cash and cash equivalents			0
Short-term Investments			0
Equity Investments			18
Cash
Cash, Cash Equivalents and Investments [Line Items]
Cash		3,881	3,942
Cash and cash equivalents		3,881	3,942
Short-term Investments		0	0
Equity Investments		0	0
Derivatives, net
Cash, Cash Equivalents and Investments [Line Items]
Derivative, net	[1]	109	104
Cash and cash equivalents	[1]	0	0
Short-term Investments	[1]	109	104
Equity Investments	[1]	0	0
Debt investments
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		133,105	130,597
Debt investments, Unrealized Gains		68	125
Debt investments, Unrealized Losses		(1,522)	(1,247)
Debt investments, Recorded Basis		131,651	129,475
Cash and cash equivalents		11,017	7,758
Short-term Investments		120,634	121,717
Equity Investments		0	0
Debt investments | Commercial Paper | Level 2
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		2,883	2,513
Debt investments, Unrealized Gains		0	0
Debt investments, Unrealized Losses		0	0
Debt investments, Recorded Basis		2,883	2,513
Cash and cash equivalents		2,784	2,215
Short-term Investments		99	298
Equity Investments		0	0
Debt investments | Certificates of deposit | Level 2
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		2,537	2,058
Debt investments, Unrealized Gains		0	0
Debt investments, Unrealized Losses		0	0
Debt investments, Recorded Basis		2,537	2,058
Cash and cash equivalents		2,081	1,865
Short-term Investments		456	193
Equity Investments		0	0
Debt investments | U.S. government securities | Level 1
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		111,281	108,120
Debt investments, Unrealized Gains		9	62
Debt investments, Unrealized Losses		(1,442)	(1,167)
Debt investments, Recorded Basis		109,848	107,015
Cash and cash equivalents		4,419	2,280
Short-term Investments		105,429	104,735
Equity Investments		0	0
Debt investments | U.S. agency securities | Level 2
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		639	1,742
Debt investments, Unrealized Gains		0	0
Debt investments, Unrealized Losses		0	0
Debt investments, Recorded Basis		639	1,742
Cash and cash equivalents		349	1,398
Short-term Investments		290	344
Equity Investments		0	0
Debt investments | Foreign government bonds | Level 2
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		4,981	5,063
Debt investments, Unrealized Gains		1	1
Debt investments, Unrealized Losses		(12)	(10)
Debt investments, Recorded Basis		4,970	5,054
Cash and cash equivalents		1,384	0
Short-term Investments		3,586	5,054
Equity Investments		0	0
Debt investments | Foreign government bonds | Level 1
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis			22
Debt investments, Unrealized Gains			0
Debt investments, Unrealized Losses			0
Debt investments, Recorded Basis			22
Cash and cash equivalents			0
Short-term Investments			22
Equity Investments			0
Debt investments | Mortgage- and asset-backed securities | Level 2
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		3,358	3,864
Debt investments, Unrealized Gains		4	4
Debt investments, Unrealized Losses		(14)	(13)
Debt investments, Recorded Basis		3,348	3,855
Cash and cash equivalents		0	0
Short-term Investments		3,348	3,855
Equity Investments		0	0
Debt investments | Corporate notes and bonds | Level 2
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		7,143	6,929
Debt investments, Unrealized Gains		22	21
Debt investments, Unrealized Losses		(53)	(56)
Debt investments, Recorded Basis		7,112	6,894
Cash and cash equivalents		0	0
Short-term Investments		7,112	6,894
Equity Investments		0	0
Debt investments | Corporate notes and bonds | Level 3
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		15	15
Debt investments, Unrealized Gains		0	0
Debt investments, Unrealized Losses		0	0
Debt investments, Recorded Basis		15	15
Cash and cash equivalents		0	0
Short-term Investments		15	15
Equity Investments		0	0
Debt investments | Municipal securities | Level 2
Cash, Cash Equivalents and Investments [Line Items]
Debt investments, Cost Basis		268	271
Debt investments, Unrealized Gains		32	37
Debt investments, Unrealized Losses		(1)	(1)
Debt investments, Recorded Basis		299	307
Cash and cash equivalents		0	0
Short-term Investments		299	307
Equity Investments		$ 0	$ 0

[1] Refer to Note 5 – Derivatives for further information on the fair value of our derivative instruments.