Investment Components, Including Associated Derivatives (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Jun. 30, 2011
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	$ 82,297		$ 70,584
Unrealized Gains	3,591		2,716
Unrealized Losses	(212)		(484)
Recorded Basis	85,676		72,816
Cash and cash equivalents	5,240	6,017	6,938	6,388	10,610	9,610
Short-term Investments	69,243		56,102
Equity and other investments	11,193		9,776
Cash
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	2,271		2,019
Unrealized Gains	0		0
Unrealized Losses	0		0
Recorded Basis	2,271		2,019
Cash and cash equivalents	2,271		2,019
Short-term Investments	0		0
Equity and other investments	0		0
Mutual funds
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	1,064		820
Unrealized Gains	0		0
Unrealized Losses	0		0
Recorded Basis	1,064		820
Cash and cash equivalents	1,064		820
Short-term Investments	0		0
Equity and other investments	0		0
Commercial paper
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	186		96
Unrealized Gains	0		0
Unrealized Losses	0		0
Recorded Basis	186		96
Cash and cash equivalents	186		96
Short-term Investments	0		0
Equity and other investments	0		0
Certificates of deposit
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	933		744
Unrealized Gains	0		0
Unrealized Losses	0		0
Recorded Basis	933		744
Cash and cash equivalents	550		342
Short-term Investments	383		402
Equity and other investments	0		0
U.S. government and agency securities
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	60,870		47,178
Unrealized Gains	139		130
Unrealized Losses	(2)		(2)
Recorded Basis	61,007		47,306
Cash and cash equivalents	69		561
Short-term Investments	60,938		46,745
Equity and other investments	0		0
Foreign government bonds
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	1,141		1,741
Unrealized Gains	34		18
Unrealized Losses	(15)		(29)
Recorded Basis	1,160		1,730
Cash and cash equivalents	0		575
Short-term Investments	1,160		1,155
Equity and other investments	0		0
Mortgage-backed securities
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	1,271		1,816
Unrealized Gains	59		82
Unrealized Losses	(1)		(2)
Recorded Basis	1,329		1,896
Cash and cash equivalents	0		0
Short-term Investments	1,329		1,896
Equity and other investments	0		0
Corporate notes and bonds
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	5,842		7,799
Unrealized Gains	261		224
Unrealized Losses	(4)		(15)
Recorded Basis	6,099		8,008
Cash and cash equivalents	1,100		2,525
Short-term Investments	4,999		5,483
Equity and other investments	0		0
Municipal securities
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	357		358
Unrealized Gains	65		58
Unrealized Losses	0		0
Recorded Basis	422		416
Cash and cash equivalents	0		0
Short-term Investments	422		416
Equity and other investments	0		0
Common and preferred stock
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	7,063		6,965
Unrealized Gains	3,033		2,204
Unrealized Losses	(190)		(436)
Recorded Basis	9,906		8,733
Cash and cash equivalents	0		0
Short-term Investments	0		0
Equity and other investments	9,906		8,733
Other investments
Cash, Cash Equivalents and Investments [Line Items]
Cost Basis	1,299		1,048
Unrealized Gains	0		0
Unrealized Losses	0		0
Recorded Basis	1,299		1,048
Cash and cash equivalents	0		0
Short-term Investments	12		5
Equity and other investments	$ 1,287		$ 1,043