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	6 Months Ended
	Jun. 30, 2014
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	$ 1,440
Less than 12 Months Unrealized Losses	(6)
12 Months or Greater Fair Value	59
12 Months or Greater Unrealized Losses	(5)
Total Fair Value	1,499
Total, Gross Unrealized Losses	(11)
US Government Agencies Debt Securities
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	400
Less than 12 Months Unrealized Losses	(1)
12 Months or Greater Fair Value	0
12 Months or Greater Unrealized Losses	0
Total Fair Value	400
Total, Gross Unrealized Losses	(1)
US Corporate Debt Securities
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	493
Less than 12 Months Unrealized Losses	(1)
12 Months or Greater Fair Value	0
12 Months or Greater Unrealized Losses	0
Total Fair Value	493
Total, Gross Unrealized Losses	(1)
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	59
12 Months or Greater Unrealized Losses	(4)
Total Fair Value	59
Total, Gross Unrealized Losses	(4)
Foreign Debt Securities
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	521
Less than 12 Months Unrealized Losses	(1)
12 Months or Greater Fair Value	0
12 Months or Greater Unrealized Losses	0
Total Fair Value	521
Total, Gross Unrealized Losses	(1)
Public Equity Securities [Member]
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	26
Less than 12 Months Unrealized Losses	(3)
12 Months or Greater Fair Value	0
12 Months or Greater Unrealized Losses	(1)
Total Fair Value	26
Total, Gross Unrealized Losses	$ (4)