Supplemental Cash Flow Information (Summary Of Supplemental Cash Flow Information) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Net cash provided by operating activities included:
Interest paid (net of amounts capitalized)	$ 478		$ 272		$ 166
Net income taxes paid to taxing authorities	140		1,605		1,362
Non-cash investing and financing activities:
Capital lease obligations increase	0		1		0
Contribution of fixed assets to joint venture	272	[1]	0		0
Property, plant and equipment sold	0		5		4
Property, plant and equipment acquired	0		5		4
Acquisition:
Fair value of MPLX units issued	$ 0		7,326	[2]	$ 0
Payable to seller			$ 50

[1] Speedway’s contribution of travel plaza locations to new joint venture with Pilot Flying J.

[2] See Note 5.