Segment and Significant Customer Information

We assess our business on a regional basis due to the effect on our financial performance of the differing characteristics of these regions, particularly with respect to competition, regulation and other factors affecting supply and demand. At December 31, 2019, our geographic reportable segments for our wholesale business are West (including geothermal), Texas and East (including Canada) and we have a separate reportable segment for our retail business. We continue to evaluate the optimal manner in which we assess our performance including our segments and future changes may result in changes to the composition of our geographic segments.

Commodity Margin is a key operational measure of profit reviewed by our chief operating decision maker to assess the performance of our segments. The tables below show our financial data for our segments (including a reconciliation of our Commodity Margin to income (loss) from operations by segment) for the periods indicated (in millions).



	Year Ended December 31, 2019
	Wholesale
	West			Texas		East			Retail			Consolidation and Elimination			Total
Total operating revenues⁽¹⁾	$	2,743		$	3,081	$	2,164		$	4,093		$	(2,009	)	$	10,072

Commodity Margin	$	1,151		$	857	$	924		$	382		$	—		$	3,314
Add: Mark-to-market commodity activity, net and other⁽²⁾	219			154		46			(131		)	(34		)	254
Less:
Operating and maintenance expense	340			269		278			148			(34		)	1,001
Depreciation and amortization expense	254			196		191			53			—			694
General and other administrative expense	35			53		45			17			—			150
Other operating expenses	31			6		42			—			—			79
Impairment losses	—			13		71			—			—			84
(Gain) on sale of assets, net	(4		)	—		(6		)	—			—			(10		)
(Income) from unconsolidated subsidiaries	—			—		(24		)	2			—			(22		)
Income from operations	714			474		373			31			—			1,592
Interest expense															609
(Gain) loss on extinguishment of debt and other (income) expense, net															95
Income before income taxes															$	888



	Year Ended December 31, 2018
	Wholesale
	West			Texas			East			Retail		Consolidation and Elimination			Total
Total operating revenues⁽¹⁾	$	1,988		$	2,860		$	1,987		$	3,976	$	(1,299	)	$	9,512

Commodity Margin	$	1,060		$	646		$	970		$	357	$	—		$	3,033
Add: Mark-to-market commodity activity, net and other⁽²⁾	(165		)	(197		)	40			84		(32		)	(270		)
Less:
Operating and maintenance expense	348			272			269			163		(32		)	1,020
Depreciation and amortization expense	269			237			180			53		—			739
General and other administrative expense	40			61			38			19		—			158
Other operating expenses	42			24			32			—		—			98
Impairment losses	—			—			10			—		—			10
(Income) from unconsolidated subsidiaries	—			—			(26		)	2		—			(24		)
Income (loss) from operations	196			(145		)	507			204		—			762
Interest expense															617
(Gain) loss on extinguishment of debt and other (income) expense, net															53
Income before income taxes															$	92



	Year Ended December 31, 2017
	Wholesale
	West			Texas			East			Retail			Consolidation and Elimination			Total
Total operating revenues⁽¹⁾	$	1,881		$	2,342		$	1,658		$	3,797		$	(926	)	$	8,752

Commodity Margin	$	970		$	552		$	790		$	396		$	—		$	2,708
Add: Mark-to-market commodity activity, net and other⁽²⁾	(19		)	(174		)	(62		)	(10		)	(29		)	(294		)
Less:
Operating and maintenance expense	361			308			302			138			(29		)	1,080
Depreciation and amortization expense	240			208			201			75			—			724
General and other administrative expense	45			66			27			17			—			155
Other operating expenses	38			14			33			—			—			85
Impairment losses	28			13			—			—			—			41
(Gain) on sale of assets, net	—			—			(27		)	—			—			(27		)
(Income) from unconsolidated subsidiaries	—			—			(24		)	2			—			(22		)
Income (loss) from operations	239			(231		)	216			154			—			378
Interest expense																621
Debt modification and extinguishment costs and other (income) expense, net																70
Loss before income taxes																$	(313	)

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(1)	Includes intersegment revenues of $530 million, $488 million and $324 million in the West, $946 million, $573 million and $361 million in Texas, $522 million, $234 million and $237 million in the East and $11 million, $4 million, $4 million in Retail for the years ended December 31, 2019, 2018 and 2017, respectively.


(2)	Includes $1 million, nil and $(8) million of lease levelization and $78 million, $104 million and $178 million of amortization expense for the years ended December 31, 2019, 2018 and 2017, respectively.

Significant Customers

For the years ended December 31, 2019, 2018 and 2017, we had no significant customer that individually accounted for more than 10% of our annual consolidated revenues.