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	3 Months Ended
	Mar. 31, 2014
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	$ 2,107
Less than 12 Months Unrealized Losses	(9)
12 Months or Greater Fair Value	60
12 Months or Greater Unrealized Losses	(5)
Total Fair Value	2,167
Total, Gross Unrealized Losses	14
US Government Agencies Debt Securities
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	757
Less than 12 Months Unrealized Losses	(2)
12 Months or Greater Fair Value	0
12 Months or Greater Unrealized Losses	0
Total Fair Value	757
Total, Gross Unrealized Losses	2
US Corporate Debt Securities
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	700
Less than 12 Months Unrealized Losses	(1)
12 Months or Greater Fair Value	0
12 Months or Greater Unrealized Losses	0
Total Fair Value	700
Total, Gross Unrealized Losses	1
High Yield Corporate Debt Securities
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	69
Less than 12 Months Unrealized Losses	(1)
12 Months or Greater Fair Value	0
12 Months or Greater Unrealized Losses	0
Total Fair Value	69
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	573
Less than 12 Months Unrealized Losses	(2)
12 Months or Greater Fair Value	0
12 Months or Greater Unrealized Losses	0
Total Fair Value	573
Total, Gross Unrealized Losses	2
Public Equity Securities [Member]
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	8
Less than 12 Months Unrealized Losses	3
12 Months or Greater Fair Value	1
12 Months or Greater Unrealized Losses	1
Total Fair Value	9
Total, Gross Unrealized Losses	$ (4)