Fair Value of Financial Assets and Liabilities Unrealized Losses on Investments by Investment Category and Length of Time in Continuous Unrealized Loss Position (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	$ 4,706
Less than 12 Months Unrealized Losses	(28)
12 Months or Greater Fair Value	86
12 Months or Greater Unrealized Losses	(4)
Total Fair Value	4,792
Total, Gross Unrealized Losses	32
US Government Agencies Debt Securities
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	2,181
Less than 12 Months Unrealized Losses	(5)
12 Months or Greater Fair Value	8
12 Months or Greater Unrealized Losses	0
Total Fair Value	2,189
Total, Gross Unrealized Losses	5
US Corporate Debt Securities
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	1,100
Less than 12 Months Unrealized Losses	(7)
12 Months or Greater Fair Value	0
12 Months or Greater Unrealized Losses	0
Total Fair Value	1,100
Total, Gross Unrealized Losses	7
High Yield Corporate Debt Securities
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	200
Less than 12 Months Unrealized Losses	(8)
12 Months or Greater Fair Value	0
12 Months or Greater Unrealized Losses	0
Total Fair Value	200
Total, Gross Unrealized Losses	8
Asset-backed Securities
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	4
Less than 12 Months Unrealized Losses	0
12 Months or Greater Fair Value	0
12 Months or Greater Unrealized Losses	0
Total Fair Value	4
Total, Gross Unrealized Losses	0
Municipal Obligations
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	342
Less than 12 Months Unrealized Losses	(2)
12 Months or Greater Fair Value	10
12 Months or Greater Unrealized Losses	0
Total Fair Value	352
Total, Gross Unrealized Losses	2
Auction Rate Securities
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	0
Less than 12 Months Unrealized Losses	0
12 Months or Greater Fair Value	68
12 Months or Greater Unrealized Losses	(4)
Total Fair Value	68
Total, Gross Unrealized Losses	4
Foreign Debt Securities
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	879
Less than 12 Months Unrealized Losses	(6)
12 Months or Greater Fair Value	0
12 Months or Greater Unrealized Losses	0
Total Fair Value	879
Total, Gross Unrealized Losses	$ 6