Income Taxes Income Taxes (Schedule of Deferred tax assets and related valuation allowances recognized for net operating and other loss carryforwards and tax carryforwards) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards	$ 1,987	$ 1,941
Tax Credit Carryforward, Valuation Allowance	(485)
Net Deferred Tax Assets, Tax Credit Carryforwards	1,502
Deferred Tax Assets, State and Local Tax Carryforwards	1,138
State and Local Tax Carryforwards, Valuation Allowance	(128)
Net Deferred Tax Assets, State and Local Tax Carryforwards	1,010
Deferred Tax Assets, Other Non-Attribute	978
Other Non-Attribute, Valuation Allowance	(33)
Net Deferred Tax Assets, Other Non-Attribute	945
Deferred Tax Assets, Gross	4,103	3,848
Deferred Tax Assets, Gross, Valuation Allowance	(646)
Deferred Tax Assets, Net of Valuation Allowance	3,457	3,266
Deferred Tax Liabilities, Gross	2,481	1,907
Deferred Tax Liabilities, Gross, Valuation Allowance	0
Deferred Tax Liabilities, Net	(2,481)
Deferred Tax Assets, Gross, Net of Deferred Tax Liabilities	1,622
Deferred Tax Assets, Valuation Allowance	(646)	$ (582)
Deferred Tax Assets, Net	976
Foreign Tax Credits [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards	1,771
Tax Credit Carryforward, Valuation Allowance	(485)
Net Deferred Tax Assets, Tax Credit Carryforwards	1,286
General Business Tax Credit Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards	191
Tax Credit Carryforward, Valuation Allowance	0
Net Deferred Tax Assets, Tax Credit Carryforwards	191
AMT credits [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Tax Credit Carryforwards	25
Tax Credit Carryforward, Valuation Allowance	0
Net Deferred Tax Assets, Tax Credit Carryforwards	25
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	900
Operating Loss Carryforwards, Valuation Allowance	0
Net Deferred Tax Assets, Operating Loss Carryforwards	900
Deferred Tax Assets, Capital Loss Carryforwards	36
Capital Loss Carryforwards, Valuation Allowance	(36)
Net Deferred Tax Assets, Capital Loss Carryforwards	0
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	193
Operating Loss Carryforwards, Valuation Allowance	(83)
Net Deferred Tax Assets, Operating Loss Carryforwards	110
Deferred Tax Assets, Capital Loss Carryforwards	9
Capital Loss Carryforwards, Valuation Allowance	(9)
Net Deferred Tax Assets, Capital Loss Carryforwards	$ 0