Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended	12 Months Ended
	Sep. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax [Line Items]
Valuation allowance against U.S. deferred tax assets, percent				100.00%
Goodwill, impairment loss				$ 873	$ 1,328
Allocated goodwill				197
Deferred tax assets, valuation allowance			$ 967	1,666	967
Foreign earnings repatriated						$ 2,800
Current income tax expense (benefit)				100	(237)	477
Deferred tax liabilities, taxes on unremitted foreign earnings				13
Current income tax expense (benefit) on repatriation after foreign tax credits						67
Deferred tax liability, other			271	426	271
Net operating loss carryforwards, deferred tax assets			175	777	175
Unremitted foreign earnings				1,000
Unremitted earnings from subsidiaries not to be permanently reinvested				47
Unrecognized tax benefits, interest and penalties			29	68	29
Unrecognized tax benefit that would impact effective tax rate				202
Interest associated with tax examinations				36
United States Federal [Member]
Income Tax [Line Items]
Net operating loss carryforwards				$ 1,500
Operating loss carryforward, expiration date				Dec. 31, 2036
Canada Federal [Member]
Income Tax [Line Items]
Net operating loss carryforwards				$ 536
Various U.S. States [Member]
Income Tax [Line Items]
Net operating loss carryforwards				$ 689
Maximum [Member] | Canada Federal [Member]
Income Tax [Line Items]
Operating loss carryforward, expiration date				Dec. 31, 2037
Maximum [Member] | Various U.S. States [Member]
Income Tax [Line Items]
Operating loss carryforward, expiration date				Dec. 31, 2036
Minimum [Member] | Canada Federal [Member]
Income Tax [Line Items]
Operating loss carryforward, expiration date				Dec. 31, 2029
Operating loss carryforward, utilization period				Dec. 31, 2017
Minimum [Member] | Various U.S. States [Member]
Income Tax [Line Items]
Operating loss carryforward, expiration date				Dec. 31, 2018
U.S. Asset Divestitures [Member]
Income Tax [Line Items]
Current income tax expense (benefit)						294
Repatriated Foreign Earnings [Member]
Income Tax [Line Items]
Current income tax expense (benefit)						105
Assumed Repatriations Of Foreign Earnings [Member]
Income Tax [Line Items]
Deferred tax liabilities, taxes on unremitted foreign earnings						143
Scenario Plan [Member]
Income Tax [Line Items]
Unrecognized tax benefits recognized				$ 88
U.S. Oil And Gas Operations [Member]
Income Tax [Line Items]
Oil and Gas asset impairment charges					18,000
General Partner And EnLink [Member]
Income Tax [Line Items]
Goodwill, impairment loss		$ 873		873	$ 1,328
Goodwill and intangibles impairments			$ 1,600
Deferred tax liability, other						46
Net operating loss carryforwards				293
Deferred tax assets, alternative minimum tax credits				$ 1
General Partner And EnLink [Member] | Maximum [Member]
Income Tax [Line Items]
Operating loss carryforward, expiration date				Dec. 31, 2036
General Partner And EnLink [Member] | Minimum [Member]
Income Tax [Line Items]
Operating loss carryforward, expiration date				Dec. 31, 2028
Operating loss carryforward, utilization period				Dec. 31, 2018
United States [Member]
Income Tax [Line Items]
Change in deferred tax valuation allowance				$ 774
Allocated goodwill	$ 197
Deferred tax assets, valuation allowance				630
Canada [Member]
Income Tax [Line Items]
Change in deferred tax valuation allowance				71
Goodwill, impairment loss						$ 1,941
Deferred tax assets, valuation allowance				$ 69