Income Taxes (Narrative) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosures [Line Items]
Deferred Tax Liabilities, Undistributed Foreign Earnings				$ 0
Undistributed Earnings of Foreign Subsidiaries				$ 4,000,000,000
Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent				(215.00%)	3.00%	(15.00%)
Effective tax rate				(137.00%)	41.00%	26.00%
Other Tax Expense (Benefit)	$ 26,000,000
Increase (decrease) in valuation allowance				$ (18,000,000)	$ (103,000,000)
Valuation allowance				876,000,000	894,000,000
Tax benefits related to tax status of operations in countries subject to reduced tax rates				20,000,000	21,000,000	$ 38,000,000
Income tax benefit (expense)				$ 188,000,000	$ (472,000,000)	$ (371,000,000)
Tax benefits related to tax status of operations in countries subject to reduced tax rates per share (in dollars per share)				$ 0.02	$ 0.02	$ 0.04
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued:
Interest on income taxes accrued				$ 10,000,000	$ 8,000,000
Unrecognized Tax Benefits, Income Tax Penalties Accrued				1,000,000	0
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense:
Unrecognized Tax Benefits, Interest on Income Taxes Expense				4,000,000	0	$ 2,000,000
Unrecognized Tax Benefits, Income Tax Penalties Expense				0	0	(1,000,000)
Uncertain Tax Positions Additional Disclosures:
Unrecognized tax benefits				369,000,000	373,000,000	394,000,000	$ 392,000,000
Unrecognized tax benefits that would impact effective tax rate				332,000,000	343,000,000	366,000,000
Unrecognized tax benefits that would impact effective tax rate portion with attributes warranting full valuation allowance				24,000,000	24,000,000	$ 24,000,000
Unrecognized tax benefits anticipated to result in net decrease of unrecognized tax benefits within 12 months, maximum				10,000,000
Federal
Income Tax Disclosures [Line Items]
Operating loss carryforwards				3,500,000,000
Operating loss carryforwards amount related to stock option deductions to be recognized in APIC				88,000,000
State and Local Jurisdiction
Income Tax Disclosures [Line Items]
Operating loss carryforwards				9,100,000,000
Foreign Tax Authority
Income Tax Disclosures [Line Items]
Operating loss carryforwards				3,100,000,000
General Business Tax Credit Carryforward
Income Tax Disclosures [Line Items]
Tax credit carryforward				20,000,000
Federal Alternative Minimum Tax
Income Tax Disclosures [Line Items]
Tax credit carryforward				5,000,000
Foreign Jurisdictions
Income Tax Disclosures [Line Items]
Tax credit carryforward				32,000,000
2021 Expiration | Foreign Jurisdictions
Income Tax Disclosures [Line Items]
Tax credit carryforward				22,000,000
No Expiration
Income Tax Disclosures [Line Items]
Tax credit carryforward				8,000,000
VIET NAM
Income Tax Disclosures [Line Items]
Income tax benefit (expense)				$ (15,000,000)	$ (8,000,000)
Tax benefits related to tax status of operations in countries subject to reduced tax rates per share (in dollars per share)				$ 0.01	$ 0.01
Chilean tax reform Member [Member]
Income Tax Disclosures [Line Items]
Effective tax rate	25.00%
Subsequent Event [Member] | Chilean tax reform Member [Member]
Income Tax Disclosures [Line Items]
Effective tax rate		27.00%	25.50%