Long-Term Debt and Credit Facilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Total Debt	$ 6,520	$ 6,544
Less: Current portion of long-term debt	0	298	[1]
Total debt, Excluding current portion of long-term debt	6,520	6,246	[1]
Short-term borrowings	$ 13	$ 4	[1]
Weighted-average interest rate on short term borrowings	1.60%	1.80%
Scheduled maturities of long-term debt [Abstract]
2017	$ 0
2018	698
2019	1,025
2020	248
2021	297
Thereafter	$ 3,307
Notes
Debt Instrument [Line Items]
Weighted average interest rate	2.00%
Maturity date range, start	Dec. 31, 2017
Maturity date range, end	Dec. 31, 2078
Total Debt	$ 6,225	$ 6,539
Commercial Paper
Debt Instrument [Line Items]
Weighted average interest rate	(0.30%)
Maturity date	2017
Total Debt	$ 295	$ 5

[1] Prior year amounts have been reclassified to conform to the current year presentation of debt issuance costs required by Accounting Standards Update (“ASU”) No. 2015-03 “Simplifying the Presentation of Debt Issuance Costs.” See Note 2, Summary of Significant Accounting Policies to the Consolidated Financial Statements for additional information.