|
Investments Measured at Fair Value on a Recurring Basis (Detail) (Fair Value, Measurements, Recurring, USD $)
In Millions, unless otherwise specified
|
Dec. 31, 2011
|
Dec. 31, 2010
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
$ 1,475 |
$ 1,150 |
|
Marketable securities
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
1,241 |
883 |
|
Marketable securities | U.S. government and agency debt securities
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
187 |
206 |
|
Marketable securities | Asset-backed Securities
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
191 |
301 |
|
Marketable securities | Corporate debt securities
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
837 |
183 |
|
Marketable securities | U.S. state and local municipal debt securities
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
15 |
78 |
|
Marketable securities | Other debt and equity securities
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
11 |
115 |
|
Other Long-term Investments
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
234 |
267 |
|
Fair Value, Inputs, Level 1
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
204 |
247 |
|
Fair Value, Inputs, Level 1 | Marketable securities
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
187 |
247 |
|
Fair Value, Inputs, Level 1 | Marketable securities | U.S. government and agency debt securities
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
187 |
206 |
|
Fair Value, Inputs, Level 1 | Marketable securities | Other debt and equity securities
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
|
41 |
|
Fair Value, Inputs, Level 1 | Other Long-term Investments
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
17 |
|
|
Fair Value, Inputs, Level 2
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
1,054 |
498 |
|
Fair Value, Inputs, Level 2 | Marketable securities
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
1,054 |
498 |
|
Fair Value, Inputs, Level 2 | Marketable securities | Asset-backed Securities
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
191 |
222 |
|
Fair Value, Inputs, Level 2 | Marketable securities | Corporate debt securities
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
837 |
183 |
|
Fair Value, Inputs, Level 2 | Marketable securities | U.S. state and local municipal debt securities
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
15 |
33 |
|
Fair Value, Inputs, Level 2 | Marketable securities | Other debt and equity securities
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
11 |
60 |
|
Fair Value, Inputs, Level 3
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
217 |
405 |
|
Fair Value, Inputs, Level 3 | Marketable securities
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
|
138 |
|
Fair Value, Inputs, Level 3 | Marketable securities | Asset-backed Securities
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
|
79 |
|
Fair Value, Inputs, Level 3 | Marketable securities | U.S. state and local municipal debt securities
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
|
45 |
|
Fair Value, Inputs, Level 3 | Marketable securities | Other debt and equity securities
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
|
14 |
|
Fair Value, Inputs, Level 3 | Other Long-term Investments
|
|
|
| Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
| Investments |
$ 217 |
$ 267 |