Fair Value of Financial Assets and Liabilities - Unrealized Losses on Investments by Investment Category and Length of Time in Continuous Unrealized Loss Position (Detail) $ in Millions	Jun. 30, 2015 USD ($)
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	$ 3,576
Less than 12 Months Gross Unrealized Losses	(20)
12 Months or Greater Fair Value	55
12 Months or Greater Gross Unrealized Losses	(10)
Total Fair Value	3,631
Total, Gross Unrealized Losses	(30)
U.S. government and agency obligations
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	664
Less than 12 Months Gross Unrealized Losses	(2)
12 Months or Greater Fair Value	0
12 Months or Greater Gross Unrealized Losses	0
Total Fair Value	664
Total, Gross Unrealized Losses	(2)
U.S. corporate debt securities
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	1,326
Less than 12 Months Gross Unrealized Losses	(7)
12 Months or Greater Fair Value	0
12 Months or Greater Gross Unrealized Losses	0
Total Fair Value	1,326
Total, Gross Unrealized Losses	(7)
High yield corporate debt securities
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	197
Less than 12 Months Gross Unrealized Losses	(8)
12 Months or Greater Fair Value	9
12 Months or Greater Gross Unrealized Losses	(1)
Total Fair Value	206
Total, Gross Unrealized Losses	(9)
Auction rate securities
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	0
Less than 12 Months Gross Unrealized Losses	0
12 Months or Greater Fair Value	26
12 Months or Greater Gross Unrealized Losses	(1)
Total Fair Value	26
Total, Gross Unrealized Losses	(1)
Foreign debt securities
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	1,389
Less than 12 Months Gross Unrealized Losses	(3)
12 Months or Greater Fair Value	0
12 Months or Greater Gross Unrealized Losses	0
Total Fair Value	1,389
Total, Gross Unrealized Losses	(3)
Publicly traded equity securities
Gain (Loss) on Investments [Line Items]
Less Than 12 Months Fair Value	0
Less than 12 Months Gross Unrealized Losses	0
12 Months or Greater Fair Value	20
12 Months or Greater Gross Unrealized Losses	(8)
Total Fair Value	20
Total, Gross Unrealized Losses	$ (8)