Long-Term Debt and Credit Facilities (Details 4) $ in Millions	Dec. 31, 2015 USD ($)	[1]
Long-term Debt, Fiscal Year Maturity [Abstract]
2016	$ 1,503
2017	1,501
2018	251
2019	1,160
2020	1,032
2021 and thereafter	15,082
Total long-term debt	$ 20,529

[1] Actual principal paid in all years may differ due to the possible future refinancing of outstanding debt or the issuance of new debt.