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, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Change in plan assets:
Fair value of plan assets at December 31	$ 1,800		$ 1,478
Amounts recognized in the consolidated balance sheets:
Noncurrent liabilities	(771)		(1,266)
LOOP [Member]
Pretax amounts recognized in accumulated other comprehensive loss:
Equity method investments, Ownership Percentage	51.00%
LOOP [Member]
Pretax amounts recognized in accumulated other comprehensive loss:
Equity method investments, Ownership Percentage	51.00%
Pension Benefits [Member]
Change in benefit obligations:
Benefit obligations at January 1	2,192		2,685
Service cost	93		66		65
Interest cost	73		94		110
Actuarial (gain) loss	(183)		117
Liability gain due to curtailment	0		(17)
Other	0	[1]	(520)	[1]
Benefit obligations at December 31	1,927		2,192		2,685
Change in plan assets:
Fair value of plan assets at January 1	1,478		1,423
Actual return on plan assets	241		157
Employer contributions	329		131
Benefits paid	(248)		(233)
Fair value of plan assets at December 31	1,800		1,478		1,423
Funded status of plans at December 31	(127)		(714)
Amounts recognized in the consolidated balance sheets:
Current liabilities	(18)		(18)
Noncurrent liabilities	(109)		(696)
Accrued benefit cost	(127)		(714)
Pretax amounts recognized in accumulated other comprehensive loss:
Net loss	668	[2]	1,147	[2]
Prior service cost (credit)	(415)	[2]	(460)	[2]
Pension Benefits [Member] | LOOP [Member]
Pretax amounts recognized in accumulated other comprehensive loss:
Net loss	16	[2]
Other Benefits [Member]
Change in benefit obligations:
Benefit obligations at January 1	591		551
Service cost	25		20		19
Interest cost	26		24		27
Actuarial (gain) loss	17		53
Liability gain due to curtailment	0		0
Other	48	[1]	(40)	[1]
Benefit obligations at December 31	687		591		551
Change in plan assets:
Benefits paid	(20)		(17)
Funded status of plans at December 31	(687)		(591)
Amounts recognized in the consolidated balance sheets:
Current liabilities	(25)		(21)
Noncurrent liabilities	(662)		(570)
Accrued benefit cost	(687)		(591)
Pretax amounts recognized in accumulated other comprehensive loss:
Net loss	107	[2]	93	[2]
Prior service cost (credit)	(30)	[2]	(38)	[2]
Other Benefits [Member] | LOOP [Member]
Pretax amounts recognized in accumulated other comprehensive loss:
Net loss	$ 2	[2]

[1] Includes adjustments related to plan amendments in 2013 and 2012. Also, includes adjustments related to the Galveston Bay Refinery and Related Assets acquisition in 2013.

[2] Amounts exclude those related to LOOP, an equity method investee with defined benefit pension and postretirement plans for which net losses of $16 million and $2 million were recorded in accumulated other comprehensive loss in 2013, reflecting our 51 percent share.