Employee Benefits - Overview of the accumulated benefit obligation, fair value of plan assets, funded status and net amount recognized for U.S. and Canadian Other Post-Retirement Benefits (Details) - U.S. and Canadian Other Post-Retirement Benefits - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accumulated projected benefit obligation	$ 110	$ 105
Fair value of plan assets	18	18
Funded status	(92)	(87)
Unrecognized prior-service credit	(3)	(3)
Unrecognized loss	10	7
Net amount recognized	$ (85)	$ (83)