Restructuring Level 4 (Details) - Restructuring by Type - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Jun. 30, 2016
Restructuring Cost and Reserve [Line Items]
Other Liabilities, Current			$ 159	$ 123
Restructuring and Related Cost, Accelerated Depreciation			(129)	$ (2)	$ 0
Norco [Member]
Restructuring Cost and Reserve [Line Items]
Loss on Contract Termination			24
Other Liabilities, Current			18
Norco Restructuring and Related Cost, Accelerated Depreciation		$ 76
Asset Retirement Obligation						$ 30
Accelerated depreciation related to asset retirement obligation			30
Asset Retirement Obligation, Revision of Estimate	$ 11
Norco ARO Liability			13
Restructuring and Related Cost, Incurred Cost			$ 16
OTG [Domain]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Accelerated Depreciation	$ 21