Investment Components, Including Associated Derivatives but Excluding Held to Maturity Investments (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Jun. 30, 2015	Sep. 30, 2014	Jun. 30, 2014
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	$ 106,740	$ 103,647
Unrealized Gains	4,726	5,220
Unrealized Losses	(698)	(313)
Recorded Basis	110,768	108,554
Cash and cash equivalents	5,431	5,595	$ 6,302	$ 8,669
Short-term Investments	93,924	90,931
Equity and Other Investments	11,413	12,028
Cash
Cash, Cash Equivalents and Investments [Line Items]
Cash	3,555	3,679
Unrealized Gains	0	0
Unrealized Losses	0	0
Cash	3,555	3,679
Cash and cash equivalents	3,555	3,679
Short-term Investments	0	0
Equity and Other Investments	0	0
Mutual funds
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	854	1,100
Unrealized Gains	0	0
Unrealized Losses	0	0
Recorded Basis	854	1,100
Cash and cash equivalents	854	1,100
Short-term Investments	0	0
Equity and Other Investments	0	0
Commercial paper
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	10	1
Unrealized Gains	0	0
Unrealized Losses	(2)	0
Recorded Basis	8	1
Cash and cash equivalents	8	1
Short-term Investments	0	0
Equity and Other Investments	0	0
Certificates of deposit
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	1,115	906
Unrealized Gains	0	0
Unrealized Losses	0	0
Recorded Basis	1,115	906
Cash and cash equivalents	965	776
Short-term Investments	150	130
Equity and Other Investments	0	0
U.S. government and agency securities
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	76,086	72,843
Unrealized Gains	96	76
Unrealized Losses	(48)	(30)
Recorded Basis	76,134	72,889
Cash and cash equivalents	49	39
Short-term Investments	76,085	72,850
Equity and Other Investments	0	0
Foreign government bonds
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	5,535	5,477
Unrealized Gains	4	3
Unrealized Losses	(40)	(24)
Recorded Basis	5,499	5,456
Cash and cash equivalents	0	0
Short-term Investments	5,499	5,456
Equity and Other Investments	0	0
Mortgage- and asset-backed securities
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	4,800	4,899
Unrealized Gains	23	23
Unrealized Losses	(6)	(6)
Recorded Basis	4,817	4,916
Cash and cash equivalents	0	0
Short-term Investments	4,817	4,916
Equity and Other Investments	0	0
Corporate notes and bonds
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	7,038	7,192
Unrealized Gains	88	97
Unrealized Losses	(79)	(37)
Recorded Basis	7,047	7,252
Cash and cash equivalents	0	0
Short-term Investments	7,047	7,252
Equity and Other Investments	0	0
Municipal securities
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	285	285
Unrealized Gains	38	35
Unrealized Losses	(1)	(1)
Recorded Basis	322	319
Cash and cash equivalents	0	0
Short-term Investments	322	319
Equity and Other Investments	0	0
Common and preferred stock
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	6,895	6,668
Unrealized Gains	4,477	4,986
Unrealized Losses	(522)	(215)
Recorded Basis	10,850	11,439
Cash and cash equivalents	0	0
Short-term Investments	0	0
Equity and Other Investments	10,850	11,439
Other investments
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	567	597
Unrealized Gains	0	0
Unrealized Losses	0	0
Recorded Basis	567	597
Cash and cash equivalents	0	0
Short-term Investments	4	8
Equity and Other Investments	$ 563	$ 589