| **Restructuring and Impairments - Restructuring Liability (Details) (USD $)In Millions, unless otherwise specified** | 6 Months Ended |
|----------------------------------------------------------------------------------------------------------------------|----------------|
||
| **Restructuring Cost and Reserve [Line Items]**                                                                      |           |   |
| Restructuring liability at beginning of year                                                                         | $ 89           | $ 39 |
| Additions                                                                                                            | 9              | 26 |
| Payments                                                                                                             | (52)           | (16) |
| Adjustments                                                                                                          | (1)            | (3) |
| Restructuring liability at end of year                                                                               | 45             | 46 |
| Employee Severance [Member]                                                                                          |           |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                      |           |   |
| Restructuring liability at beginning of year                                                                         | 72             | 31 |
| Additions                                                                                                            | 1              | 2 |
| Payments                                                                                                             | (44)           | (4) |
| Adjustments                                                                                                          | (3)            | (3) |
| Restructuring liability at end of year                                                                               | 26             | 26 |
| Employee Relocation [Member]                                                                                         |           |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                      |           |   |
| Restructuring liability at beginning of year                                                                         | 0              | 0 |
| Additions                                                                                                            | 2              | 4 |
| Payments                                                                                                             | (2)            | (4) |
| Adjustments                                                                                                          | 0              | 0 |
| Restructuring liability at end of year                                                                               | 0              | 0 |
| Lease Vacancy [Member]                                                                                               |           |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                      |           |   |
| Restructuring liability at beginning of year                                                                         | 17             | 0 |
| Additions                                                                                                            | 2              | 19 |
| Payments                                                                                                             | (3)            | (1) |
| Adjustments                                                                                                          | 2              | 0 |
| Restructuring liability at end of year                                                                               | 18             | 18 |
| Other Restructuring [Member]                                                                                         |           |   |
| **Restructuring Cost and Reserve [Line Items]**                                                                      |           |   |
| Restructuring liability at beginning of year                                                                         | 0              | 8 |
| Additions                                                                                                            | 4              | 1 |
| Payments                                                                                                             | (3)            | (7) |
| Adjustments                                                                                                          | 0              | 0 |
| Restructuring liability at end of year                                                                               | $ 1            | $ 2 |

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| - Definition
Discloses the amount charged against the accrued restructuring reserves, or earnings if not previously accrued, during the period for the specified type of restructuring cost.
+ References
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|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan.
+ References
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|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of any reversal and other adjustment made during the period to the amount of a previously accrued liability for a specified type of restructuring cost, excluding adjustments for costs incurred during the period, costs settled during the period, and foreign currency translation adjustments.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 5 -Section P -Subsection 3, 4Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 146 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Emerging Issues Task Force (EITF) -Number 95-3 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.  This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 420 -SubTopic 10 -Section 40 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6394291&loc=d3e17658-110867Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 420 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 420 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SAB TOPIC 5.P.4(b)) -URI http://asc.fasb.org/extlink&oid=6394695&loc=d3e140904-122747
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|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount of cash paid in the period to fully or partially settle a specified, previously accrued type of restructuring cost.
+ References
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