The following table reflects the components of operating income by reportable segment (in millions):



	Refining		Ethanol		VLP		Corporate and Eliminations			Total
Three months ended June 30, 2018:
Revenues:
Revenues from external customers	$	30,130	$	884	$	—	$	1		$	31,015
Intersegment revenues	1		42		135		(178		)	—
Total revenues	30,131		926		135		(177		)	31,015
Cost of sales:
Cost of materials and other	27,283		754		—		(177		)	27,860
Operating expenses (excluding depreciation and amortization expense reflected below)	969		109		33		(1		)	1,110
Depreciation and amortization expense	471		20		19		—			510
Total cost of sales	28,723		883		52		(178		)	29,480
Other operating expenses	21		—		—		—			21
General and administrative expenses (excluding depreciation and amortization expense reflected below)	—		—		—		248			248
Depreciation and amortization expense	—		—		—		13			13
Operating income by segment	$	1,387	$	43	$	83	$	(260	)	$	1,253

Three months ended June 30, 2017:
Revenues:
Revenues from external customers	$	21,415	$	839	$	—	$	—		$	22,254
Intersegment revenues	—		28		110		(138		)	—
Total revenues	21,415		867		110		(138		)	22,254
Cost of sales:
Cost of materials and other	19,037		710		—		(138		)	19,609
Operating expenses (excluding depreciation and amortization expense reflected below)	979		107		27		(2		)	1,111
Depreciation and amortization expense	454		19		12		—			485
Total cost of sales	20,470		836		39		(140		)	21,205
General and administrative expenses (excluding depreciation and amortization expense reflected below)	—		—		—		175			175
Depreciation and amortization expense	—		—		—		14			14
Operating income by segment	$	945	$	31	$	71	$	(187	)	$	860



	Refining		Ethanol		VLP		Corporate and Eliminations			Total
Six months ended June 30, 2018:
Revenues:
Revenues from external customers	$	55,691	$	1,761	$	—	$	2		$	57,454
Intersegment revenues	5		88		267		(360		)	—
Total revenues	55,696		1,849		267		(358		)	57,454
Cost of sales:
Cost of materials and other	50,471		1,503		—		(358		)	51,616
Operating expenses (excluding depreciation and amortization expense reflected below)	1,966		220		62		(2		)	2,246
Depreciation and amortization expense	919		38		38		—			995
Total cost of sales	53,356		1,761		100		(360		)	54,857
Other operating expenses	31		—		—		—			31
General and administrative expenses (excluding depreciation and amortization expense reflected below)	—		—		—		486			486
Depreciation and amortization expense	—		—		—		26			26
Operating income by segment	$	2,309	$	88	$	167	$	(510	)	$	2,054

Six months ended June 30, 2017:
Revenues:
Revenues from external customers	$	42,302	$	1,724	$	—	$	—		$	44,026
Intersegment revenues	—		88		216		(304		)	—
Total revenues	42,302		1,812		216		(304		)	44,026
Cost of sales:
Cost of materials and other	37,844		1,497		—		(304		)	39,037
Operating expenses (excluding depreciation and amortization expense reflected below)	1,970		216		51		(2		)	2,235
Depreciation and amortization expense	903		46		24		—			973
Total cost of sales	40,717		1,759		75		(306		)	42,245
General and administrative expenses (excluding depreciation and amortization expense reflected below)	—		—		—		367			367
Depreciation and amortization expense	—		—		—		26			26
Operating income by segment	$	1,585	$	53	$	141	$	(391	)	$	1,388

The following table provides a disaggregation of revenues by reportable segment (in millions). Refining and ethanol segment revenues are disaggregated for our principal products, and VLP segment revenues are disaggregated by activity type.



	Three Months Ended June 30,						Six Months Ended June 30,
	2018			2017			2018			2017
Refining:
Gasolines and blendstocks	$	12,514		$	9,723		$	23,143		$	19,058
Distillates	14,459			9,736			27,117			19,432
Other product revenues	3,157			1,956			5,431			3,812
Total refining revenues	30,130			21,415			55,691			42,302
Ethanol:
Ethanol	696			712			1,397			1,462
Distillers grains	188			127			364			262
Total ethanol revenues	884			839			1,761			1,724
VLP:
Pipeline transportation	31			25			62			48
Terminaling	103			84			202			167
Storage and other	1			1			3			1
Total VLP revenues	135			110			267			216
Corporate – other revenues	1			—			2			—
Elimination of intersegment revenues	(135		)	(110		)	(267		)	(216		)
Revenues	$	31,015		$	22,254		$	57,454		$	44,026

Total assets by reportable segment were as follows (in millions):



	June 30, 2018		December 31, 2017
Refining	$	42,107	$	40,382
Ethanol	1,332		1,344
VLP	1,569		1,517
Corporate and eliminations	5,670		6,915
Total assets	$	50,678	$	50,158