Unrealized Loss Position Investments (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Jun. 30, 2012
Unrealized Losses on Investments [Line Items]
Less than 12 Months - Fair Value	$ 1,839	$ 3,529
Less than 12 Months - Unrealized Losses	(112)	(369)
12 Months or Greater - Fair Value	577	435
12 Months or Greater - Unrealized Losses	(100)	(115)
Total Fair Value	2,416	3,964
Total Unrealized Losses	(212)	(484)
U.S. government and agency securities
Unrealized Losses on Investments [Line Items]
Less than 12 Months - Fair Value	213	44
Less than 12 Months - Unrealized Losses	(2)	(2)
12 Months or Greater - Fair Value	0	0
12 Months or Greater - Unrealized Losses	0	0
Total Fair Value	213	44
Total Unrealized Losses	(2)	(2)
Foreign government bonds
Unrealized Losses on Investments [Line Items]
Less than 12 Months - Fair Value	151	657
Less than 12 Months - Unrealized Losses	(2)	(27)
12 Months or Greater - Fair Value	79	12
12 Months or Greater - Unrealized Losses	(13)	(2)
Total Fair Value	230	669
Total Unrealized Losses	(15)	(29)
Mortgage-backed securities
Unrealized Losses on Investments [Line Items]
Less than 12 Months - Fair Value	52	53
Less than 12 Months - Unrealized Losses	0	0
12 Months or Greater - Fair Value	42	48
12 Months or Greater - Unrealized Losses	(1)	(2)
Total Fair Value	94	101
Total Unrealized Losses	(1)	(2)
Corporate notes and bonds
Unrealized Losses on Investments [Line Items]
Less than 12 Months - Fair Value	364	640
Less than 12 Months - Unrealized Losses	(1)	(11)
12 Months or Greater - Fair Value	30	70
12 Months or Greater - Unrealized Losses	(3)	(4)
Total Fair Value	394	710
Total Unrealized Losses	(4)	(15)
Common and preferred stock
Unrealized Losses on Investments [Line Items]
Less than 12 Months - Fair Value	1,059	2,135
Less than 12 Months - Unrealized Losses	(107)	(329)
12 Months or Greater - Fair Value	426	305
12 Months or Greater - Unrealized Losses	(83)	(107)
Total Fair Value	1,485	2,440
Total Unrealized Losses	$ (190)	$ (436)