Basis of Presentation (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Summary of Reclassification From Prior Period [Line Items]
Prepaid pension	$ 737		$ 1,033
Reclassification adjustment, amount transferred from operating activities to issuance of shares for employee benefit plans in financing activities	128	$ 162
Reclassification adjustment, amount transferred from account payable and accrued liabilities in operating activities to financing activities		118
Reclassification Adjustment, amount transferred from other assets and liabilities in operating activities to financing activities		44
Noncontrolling interests and other financing activities	$ (42)	(6)
Scenario, Previously Reported [Member]
Summary of Reclassification From Prior Period [Line Items]
Noncontrolling interests and other financing activities		(5)
Dividends paid to noncontrolling interests		$ (1)
Accounting Standard Update 2015-03 [Member] | Other Current Assets [Member]
Summary of Reclassification From Prior Period [Line Items]
Deferred Finance Costs, Net			4
Accounting Standard Update 2015-03 [Member] | Other Noncurrent Assets [Member]
Summary of Reclassification From Prior Period [Line Items]
Deferred Finance Costs, Net			$ 33