v3.4.0.3
Segment Information
 3 Months Ended
Mar. 31, 2016
Segment Reporting [Abstract]  
Segment Information
Segment Information
We assess our business on a regional basis due to the impact on our financial performance of the differing characteristics of these regions, particularly with respect to competition, regulation and other factors impacting supply and demand. At March 31, 2016, our reportable segments were West (including geothermal), Texas and East (including Canada). 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 reviewed by our chief operating decision maker to assess the performance of our segments. The tables below show our financial data for our segments for the periods indicated (in millions).

 
Three Months Ended March 31, 2016
 
West
 
Texas
 
East
 
Consolidation
and
Elimination
 
Total
Revenues from external customers
$
424

 
$
532

 
$
659

 
$
—

 
$
1,615

Intersegment revenues
2

 
3

 
3

 
(8
)
 
—

Total operating revenues
$
426

 
$
535

 
$
662

 
$
(8
)
 
$
1,615

Commodity Margin
$
197

 
$
153

 
$
230

 
$
—

 
$
580

Add: Mark-to-market commodity activity, net and other(1)
46

 
(110
)
 
(21
)
 
(6
)
 
(91
)
Less:
 
 
 
 
 
 
 
 
 
Plant operating expense
91

 
86

 
84

 
(6
)
 
255

Depreciation and amortization expense
69

 
53

 
58

 
—

 
180

Sales, general and other administrative expense
10

 
16

 
12

 
—

 
38

Other operating expenses
8

 
2

 
10

 
—

 
20

(Income) from unconsolidated investments in power plants
—

 
—

 
(7
)
 
—

 
(7
)
Income (loss) from operations
65

 
(114
)
 
52

 
—

 
3

Interest expense, net of interest income
 
 
 
 
 
 
 
 
156

Other (income) expense, net
 
 
 
 
 
 
 
 
6

Loss before income taxes
 
 
 
 
 
 
 
 
$
(159
)

 
Three Months Ended March 31, 2015
 
West
 
Texas
 
East
 
Consolidation
and
Elimination
 
Total
Revenues from external customers
$
515

 
$
581

 
$
550

 
$
—

 
$
1,646

Intersegment revenues
2

 
3

 
2

 
(7
)
 
—

Total operating revenues
$
517

 
$
584

 
$
552

 
$
(7
)
 
$
1,646

Commodity Margin
$
218

 
$
149

 
$
168

 
$
—

 
$
535

Add: Mark-to-market commodity activity, net and other(1)
119

 
41

 
(52
)
 
(7
)
 
101

Less:
 
 
 
 
 
 
 
 
 
Plant operating expense
106

 
89

 
72

 
(7
)
 
260

Depreciation and amortization expense
67

 
49

 
42

 
—

 
158

Sales, general and other administrative expense
10

 
17

 
10

 
—

 
37

Other operating expenses
10

 
2

 
8

 
—

 
20

(Income) from unconsolidated investments in power plants
—

 
—

 
(5
)
 
—

 
(5
)
Income (loss) from operations
144


33


(11
)

—

 
166

Interest expense, net of interest income
 
 
 
 
 
 
 
 
153

Debt extinguishment costs and other (income) expense, net
 
 
 
 
 
 
 
 
21

Loss before income taxes
 
 
 
 
 
 
 
 
$
(8
)
_________
(1)
Includes $(22) million and $(24) million of lease levelization and $27 million and $4 million of amortization expense for the three months ended March 31, 2016 and 2015, respectively.