| 
           Income Taxes Deferred taxes (Details) (USD $) 
        In Millions, unless otherwise specified  | 
        
           Dec. 31, 2012 
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           Dec. 31, 2011 
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|---|---|---|
| Income Taxes [Abstract] | ||
| Net operating and capital loss carryforwards | $ 46 | $ 76 | 
| Accrued stock compensation | 7 | 41 | 
| Other accrued liabilities | 42 | 60 | 
| Deferred revenue | 16 | 18 | 
| Other future deductible amounts | 9 | 31 | 
| Deferred tax assets | 120 | 226 | 
| Valuation allowance | (6) | (30) | 
| Net deferred tax assets | 114 | 196 | 
| Investments | 794 | 417 | 
| Intangible assets | 90 | 100 | 
| Other | 19 | 27 | 
| Deferred tax liabilities | 903 | 544 | 
| Net deferred tax liabilities | $ 789 | $ 348 | 
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- Details 
          
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- Definition 
          Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from deferred income. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards, net of deferred tax liability attributable to taxable temporary differences. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Amount before allocation of valuation allowances of deferred tax asset attributable to deductible domestic operating loss carryforwards. Excludes state and local operating loss carryforwards. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences not separately disclosed. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from share-based compensation. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from accrued liabilities. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Amount of deferred tax liability attributable to taxable temporary differences net of deferred tax asset attributable to deductible temporary differences and carryforwards after valuation allowances. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Amount of deferred tax liability attributable to taxable temporary differences from intangible assets other than goodwill. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Amount of deferred tax liability attributable to taxable temporary differences from investments in unconsolidated subsidiaries and investments in other affiliates which are not controlled nor consolidated. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Amount of deferred tax liability attributable to taxable temporary differences not separately disclosed. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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