Restructuring Level 4 (Details) - Restructuring by Type - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost Savings			$ 43
Restructuring Reserve			17	$ 0
Other Liabilities, Current			135	159
Restructuring and Related Cost, Accelerated Depreciation			(14)	(129)	$ 2
Restructuring costs expected to be incurred			28
Cumulative restructuring costs, Incurred to Date			20
Accelerated Depreciation			14	129	$ 2
Payments for Restructuring		$ (3)
Contract Termination [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve			0	18
Restructuring Reserve, Period Increase (Decrease)			(18)
Norco [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve			0	31
RestructuringReserveIncludedInAccountsPayable			1
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			11
Restructuring and Related Cost, Incurred Cost			3	24
Payments for Restructuring			30
Restructuring Reserve, Period Increase (Decrease)			(31)
Other projects [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve			0	13
Loss on Contract Termination				16
Restructuring Reserve, Period Increase (Decrease)			(13)
OTG [Domain]
Restructuring Cost and Reserve [Line Items]
Accelerated Depreciation			14	21
EPCD [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve			11	0
Restructuring costs expected to be incurred			16
Cumulative restructuring costs, Incurred to Date			12
Payments for Restructuring		(1)
FPD [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve			3	0
Restructuring costs expected to be incurred			4
Cumulative restructuring costs, Incurred to Date			5
Payments for Restructuring		(2)
Corporate and Other [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve			3	$ 0
Restructuring costs expected to be incurred			8
Cumulative restructuring costs, Incurred to Date			$ 3
Payments for Restructuring		$ 0