Acquisitions (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended				6 Months Ended	9 Months Ended
	Mar. 18, 2019	Jun. 30, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Mar. 17, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Impairment of equity-method investments			$ 114			$ 0		$ 186	$ 0
Changes in ownership of consolidated subsidiaries, net			1			0		142	(4)
Northeast JV [Member]
Business Acquisition [Line Items]
Noncontrolling Interest in Joint Ventures		$ 1,330		$ 1,330
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		35.00%		35.00%
Subsidiary of Limited Liability Company or Limited Partnership, Ownership Interest		65.00%
Increase (Decrease) in Deferred Income Taxes								(142)
Selling, general, and administrative expenses [Member] | Northeast JV [Member]
Business Acquisition [Line Items]
Business Combination, Acquisition Related Costs								6
Fair Value, Nonrecurring [Member] | Level 3 [Member] | Impairment Of Equity-Method Investments [Member]
Business Acquisition [Line Items]
Impairment of equity-method investments								(1)
Utica East Ohio Midstream, LLC [Member]
Business Acquisition [Line Items]
Equity Method Investment, Ownership Percentage											62.00%
Utica East Ohio Midstream, LLC [Member] | Fair Value, Nonrecurring [Member] | Level 3 [Member] | Northeast G And P [Member] | Impairment Of Equity-Method Investments [Member]
Business Acquisition [Line Items]
Impairment of equity-method investments					$ 74
Utica East Ohio Midstream, LLC Acquisition [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 741
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain (Loss), Net	0
Goodwill, Purchase Accounting Adjustments				$ 169
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment				(106)
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles				$ (61)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents	13
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets	55
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	1,387
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	328
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	1,770
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities	7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net	1,763
Goodwill	188
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net	1,951
Business Acquisition, Goodwill, Expected Tax Deductible Amount	$ 188
Finite-Lived Intangible Assets, Remaining Amortization Period	20 years
Percentage Of Finite Lived Intangible Assets Impacted By Our Intent Or Ability To Renew Or Extend Arrangement	49.00%
Acquired Finite-lived Intangible Asset, Weighted-Average Period before Renewal or Extension	10 years
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual							$ 104
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual							$ 25
Utica East Ohio Midstream, LLC Acquisition [Member] | Pro Forma [Member]
Business Acquisition [Line Items]
Business Acquisition, Pro Forma Revenue			1,999			2,342		6,126	6,589
Business Acquisition, Pro Forma Net Income (Loss)			221			138		804	434
Utica East Ohio Midstream, LLC Acquisition [Member] | Selling, general, and administrative expenses [Member]
Business Acquisition [Line Items]
Business Combination, Acquisition Related Costs								4
Utica East Ohio Midstream, LLC Acquisition [Member] | Utica East Ohio Midstream, LLC [Member]
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired	38.00%
Business Combination, Step Acquisition, Equity Interest in Acquiree, Percentage										62.00%
Noncontrolling Interests
Business Acquisition [Line Items]
Changes in ownership of consolidated subsidiaries, net			2			(1)		568	(18)
Noncontrolling Interests | Northeast JV [Member]
Business Acquisition [Line Items]
Changes in ownership of consolidated subsidiaries, net								568
Capital in excess of par value [Member]
Business Acquisition [Line Items]
Changes in ownership of consolidated subsidiaries, net			$ (1)			$ 1		(426)	$ 14
Capital in excess of par value [Member] | Northeast JV [Member]
Business Acquisition [Line Items]
Changes in ownership of consolidated subsidiaries, net								$ (426)