Income Taxes Level 4 Current and Deferred Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Income Tax Contingency [Line Items]
Income Taxes Receivable		$ 5
Deferred Tax Assets, Operating Loss Carryforwards	$ 1,831	1,936
Deferred Tax Assets, Operating Loss Carryforwards, Foreign		8
Operating Loss Carryforwards, Valuation Allowance	78	172
Deferred Tax Assets, Operating Loss Carryforwards, Domestic		1,928
Domestic Tax Authority [Member]
Income Tax Contingency [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	5,182
Deferred Tax Assets, Operating Loss Carryforwards	1,814
Operating Loss Carryforwards		5,508
Foreign Tax Authority [Member]
Income Tax Contingency [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	89
Deferred Tax Assets, Operating Loss Carryforwards	$ 17
Operating Loss Carryforwards		$ 39

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible domestic operating loss carryforwards. Excludes state and local operating loss carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible foreign operating loss carryforwards.

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Carrying amount as of the balance sheet date of income taxes previously overpaid to tax authorities (such as U.S. Federal, state and local tax authorities) representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes. Also called income tax refund receivable.

+ References

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Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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The portion of the valuation allowance pertaining to the deferred tax asset representing potential future taxable deductions from net operating loss carryforwards for which it is more likely than not that a tax benefit will not be realized.

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