Defined Benefit Pension And Other Postretirement Plans (Summary Of Projected Benefit Obligations And Funded Status For Defined Benefit Pension And Other Postretirement Plans) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Change in plan assets:
Fair value of plan assets at January 1		$ 1,744
Fair value of plan assets at December 31		1,570	$ 1,744
Amounts recognized in the consolidated balance sheets:
Noncurrent liabilities		(1,179)	(1,099)
Pension Benefits
Change in benefit obligations:
Benefit obligations at January 1		2,075	1,927
Service cost		101	88	$ 93
Interest cost		71	74	73
Actuarial (gain) loss		(63)	257
Benefits paid		(187)	(271)
Other		0	0
Benefit obligations at December 31		1,997	2,075	1,927
Change in plan assets:
Fair value of plan assets at January 1		1,744	1,800
Actual return on plan assets		(33)	175
Employer contributions		46	40
Benefits paid		(187)	(271)
Fair value of plan assets at December 31		1,570	1,744	1,800
Funded status of plans at December 31		(427)	(331)
Amounts recognized in the consolidated balance sheets:
Current liabilities		(19)	(17)
Noncurrent liabilities		(408)	(314)
Accrued benefit cost		(427)	(331)
Pretax amounts recognized in accumulated other comprehensive loss:
Net loss	[1]	723	710
Prior service credit	[1]	(323)	(369)
Pension Benefits | LOOP LLC and Explorer Pipeline [Member]
Pretax amounts recognized in accumulated other comprehensive loss:
Net loss	[1]	19
Other Benefits
Change in benefit obligations:
Benefit obligations at January 1		812	687
Service cost		31	27	25
Interest cost		32	33	26
Actuarial (gain) loss		(63)	86
Benefits paid		(24)	(23)
Other	[2]	12	2
Benefit obligations at December 31		800	812	$ 687
Change in plan assets:
Benefits paid		(24)	(23)
Funded status of plans at December 31		(800)	(812)
Amounts recognized in the consolidated balance sheets:
Current liabilities		(29)	(27)
Noncurrent liabilities		(771)	(785)
Accrued benefit cost		(800)	(812)
Pretax amounts recognized in accumulated other comprehensive loss:
Net loss	[1]	120	191
Prior service credit	[1]	(9)	$ (26)
Other Benefits | LOOP LLC and Explorer Pipeline [Member]
Pretax amounts recognized in accumulated other comprehensive loss:
Net loss	[1]	$ 2

[1] Amounts exclude those related to LOOP and Explorer, equity method investees with defined benefit pension and postretirement plans for which net losses of $19 million and $2 million were recorded in accumulated other comprehensive loss in 2015, reflecting our ownership share.

[2] Includes adjustments related to the MarkWest Merger in 2015 and the acquisition of Hess’ Retail Operations and Related Assets in 2014.