Fair Value of Financial Assets and Liabilities - Additional Information (Detail) $ in Millions	12 Months Ended
Dec. 31, 2015 USD ($) Security	Dec. 31, 2014 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Number of Auction Rate Securities With Underlying Loans Which Have No Guarantees \| Security	1
Gain on sale of investment		$ 101
Auction rate securities that have partial guarantees by the U.S. government, market value	$ 6
Percentage of loans which collateralize auction rate securities guaranteed by FFELP	95.00%
Discount rate used to estimate fair value of investments	1.00%
Investment holding period	5 years
The rate used for the discount margin to determine the estimated fair value of investment in auction rate securities	1.00%	1.00%
Short term investment, not classified in investments due within one year	$ 2,726	$ 1,978
Minimum
Schedule of Available-for-sale Securities [Line Items]
Coupon rate used to estimate fair value of invesments - low end of range	1.00%
Maximum
Schedule of Available-for-sale Securities [Line Items]
Coupon rate used to estimate fair value of invesments - high end of range	3.00%
Municipal obligations
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	$ 732	950
Publicly traded equity securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	158	209
High yield corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	287	563
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	20	53
Securities (Assets)
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	8,234	8,312
Foreign debt securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	$ 2,323	2,564
Average credit rating	A+
Foreign Sovereign Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Average credit rating	AA+
Percentage of securities deemed soverign debt	4.00%
Auction rate securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities	$ 25	$ 27
Average credit rating	AA
Change in fair value of level 3 investment	no material changes
Variable Rate Demand Note
Schedule of Available-for-sale Securities [Line Items]
Short term investment, not classified in investments due within one year	$ 5
Contractual maturity date	Dec. 31, 2016
LenovoEMC
Schedule of Available-for-sale Securities [Line Items]
Joint Venture, Ownership Interest Percentage	49.00%
Discount rate used to estimate fair value of investments	6.00%
Change in fair value of level 3 investment	no material change	no material change

Auction rate securities, at Fair Value

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Description of the average credit rating indicative of likelihood of repayment of debt instruments given by credit rating agencies (for example, Standard and Poor's, Moody's, Fitch).

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Change in fair value of level 3 investment

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Financial Instruments Fair Value Assumptions Weighted Average Discount Rate

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The highest interest rate in the aggregated short-tem debt instruments.

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Joint Venture, Ownership Interest Percentage

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Number of Auction Rate Securities With Underlying Loans Which Have No Guarantees

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

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The difference between the carrying value and the sale price of an investment. A gain would be recognized when the sale price of the investment is greater than the carrying value of the investment. This element refers to the Gain included in earnings and not to the cash proceeds of the sale.

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