| Segment and Significant Customer 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 September 30, 2012, our reportable segments were West (including geothermal), Texas, North (including Canada) and Southeast. We continue to evaluate the optimal manner in which we assess our performance including our segments and future changes may result. 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 September 30, 2012 | | West | | Texas | | North | | Southeast | | Consolidation and Elimination | | Total | Revenues from external customers | $ | 509 |
| | $ | 886 |
| | $ | 407 |
| | $ | 194 |
| | $ | — |
| | $ | 1,996 |
| Intersegment revenues | 2 |
| | (34 | ) | | 4 |
| | 68 |
| | (40 | ) | | — |
| Total operating revenues | $ | 511 |
| | $ | 852 |
| | $ | 411 |
| | $ | 262 |
| | $ | (40 | ) | | $ | 1,996 |
| Commodity Margin(1) | $ | 330 |
| | $ | 218 |
| | $ | 266 |
| | $ | 83 |
| | $ | — |
| | $ | 897 |
| Add: Mark-to-market commodity activity, net and other(2)(3) | (40 | ) | | 249 |
| | (26 | ) | | 27 |
| | (8 | ) | | 202 |
| Less: | | | | | | | | | | | | Plant operating expense | 88 |
| | 49 |
| | 51 |
| | 29 |
| | (10 | ) | | 207 |
| Depreciation and amortization expense | 52 |
| | 35 |
| | 33 |
| | 21 |
| | (1 | ) | | 140 |
| Sales, general and other administrative expense | 9 |
| | 12 |
| | 8 |
| | 8 |
| | (1 | ) | | 36 |
| Other operating expenses(4) | 10 |
| | 1 |
| | 6 |
| | (1 | ) | | 2 |
| | 18 |
| (Income) from unconsolidated investments in power plants | — |
| | — |
| | (7 | ) | | — |
| | — |
| | (7 | ) | Income from operations | 131 |
| | 370 |
| | 149 |
| | 53 |
| | 2 |
| | 705 |
| Interest expense, net of interest income | | | | | | | | | | | 181 |
| Other (income) expense, net | | | | | | | | | | | 6 |
| Income before income taxes | | | | | | | | | | | $ | 518 |
|
| | | | | | | | | | | | | | | | | | | | | | | | | | Three Months Ended September 30, 2011 | | West | | Texas | | North | | Southeast | | Consolidation and Elimination | | Total | Revenues from external customers | $ | 688 |
| | $ | 843 |
| | $ | 430 |
| | $ | 248 |
| | $ | — |
| | $ | 2,209 |
| Intersegment revenues | 3 |
| | 3 |
| | (8 | ) | | 31 |
| | (29 | ) | | — |
| Total operating revenues | $ | 691 |
| | $ | 846 |
| | $ | 422 |
| | $ | 279 |
| | $ | (29 | ) | | $ | 2,209 |
| Commodity Margin(1) | $ | 329 |
| | $ | 162 |
| | $ | 259 |
| | $ | 75 |
| | $ | — |
| | $ | 825 |
| Add: Mark-to-market commodity activity, net and other(2)(3) | 20 |
| | (21 | ) | | (11 | ) | | — |
| | (8 | ) | | (20 | ) | Less: | | | | | | | | | | | | Plant operating expense | 94 |
| | 50 |
| | 44 |
| | 33 |
| | (9 | ) | | 212 |
| Depreciation and amortization expense | 52 |
| | 34 |
| | 36 |
| | 22 |
| | (1 | ) | | 143 |
| Sales, general and other administrative expense | 10 |
| | 10 |
| | 7 |
| | 7 |
| | (1 | ) | | 33 |
| Other operating expenses(4) | 11 |
| | (1 | ) | | 7 |
| | — |
| | 2 |
| | 19 |
| (Income) from unconsolidated investments in power plants | — |
| | — |
| | (5 | ) | | — |
| | — |
| | (5 | ) | Income from operations | 182 |
| | 48 |
| | 159 |
| | 13 |
| | 1 |
| | 403 |
| Interest expense, net of interest income | | | | | | | | | | | 190 |
| Loss on interest rate derivatives | | | | | | | | | | | 3 |
| Debt extinguishment costs and other (income) expense, net | | | | | | | | | | | — |
| Income before income taxes | | | | | | | | | | | $ | 210 |
|
| | | | | | | | | | | | | | | | | | | | | | | | | | Nine Months Ended September 30, 2012 | | West | | Texas | | North | | Southeast | | Consolidation and Elimination | | Total | Revenues from external customers | $ | 1,183 |
| | $ | 1,430 |
| | $ | 974 |
| | $ | 524 |
| | $ | — |
| | $ | 4,111 |
| Intersegment revenues | 7 |
| | 27 |
| | 9 |
| | 84 |
| | (127 | ) | | — |
| Total operating revenues | $ | 1,190 |
| | $ | 1,457 |
| | $ | 983 |
| | $ | 608 |
| | $ | (127 | ) | | $ | 4,111 |
| Commodity Margin(1) | $ | 748 |
| | $ | 472 |
| | $ | 591 |
| | $ | 212 |
| | $ | — |
| | $ | 2,023 |
| Add: Mark-to-market commodity activity, net and other(2)(5) | (80 | ) | | 66 |
| | (17 | ) | | (5 | ) | | (22 | ) | | (58 | ) | Less: | | | | | | | | | | | | Plant operating expense | 281 |
| | 189 |
| | 154 |
| | 98 |
| | (23 | ) | | 699 |
| Depreciation and amortization expense | 151 |
| | 104 |
| | 100 |
| | 66 |
| | (3 | ) | | 418 |
| Sales, general and other administrative expense | 23 |
| | 36 |
| | 22 |
| | 23 |
| | — |
| | 104 |
| Other operating expenses(4) | 30 |
| | 4 |
| | 21 |
| | 2 |
| | 1 |
| | 58 |
| (Income) from unconsolidated investments in power plants | — |
| | — |
| | (21 | ) | | — |
| | — |
| | (21 | ) | Income from operations | 183 |
|
| 205 |
|
| 298 |
|
| 18 |
|
| 3 |
| | 707 |
| Interest expense, net of interest income | | | | | | | | | | | 545 |
| Loss on interest rate derivatives | | | | | | | | | | | 14 |
| Debt extinguishment costs and other (income) expense, net | | | | | | | | | | | 26 |
| Income before income taxes | | | | | | | | | | | $ | 122 |
|
| | | | | | | | | | | | | | | | | | | | | | | | | | Nine Months Ended September 30, 2011 | | West | | Texas | | North | | Southeast | | Consolidation and Elimination | | Total | Revenues from external customers | $ | 1,753 |
| | $ | 1,939 |
| | $ | 1,025 |
| | $ | 624 |
| | $ | — |
| | $ | 5,341 |
| Intersegment revenues | 7 |
| | 13 |
| | 5 |
| | 116 |
| | (141 | ) | | — |
| Total operating revenues | $ | 1,760 |
| | $ | 1,952 |
| | $ | 1,030 |
| | $ | 740 |
| | $ | (141 | ) | | $ | 5,341 |
| Commodity Margin(1) | $ | 798 |
| | $ | 357 |
| | $ | 578 |
| | $ | 188 |
| | $ | — |
| | $ | 1,921 |
| Add: Mark-to-market commodity activity, net and other(2)(5) | 36 |
| | (54 | ) | | (12 | ) | | (4 | ) | | (23 | ) | | (57 | ) | Less: | | | | | | | | | | | | Plant operating expense | 297 |
| | 193 |
| | 136 |
| | 107 |
| | (22 | ) | | 711 |
| Depreciation and amortization expense | 140 |
| | 99 |
| | 102 |
| | 67 |
| | (3 | ) | | 405 |
| Sales, general and other administrative expense | 29 |
| | 33 |
| | 19 |
| | 18 |
| | — |
| | 99 |
| Other operating expenses(4) | 30 |
| | 2 |
| | 23 |
| | 3 |
| | (1 | ) | | 57 |
| (Income) from unconsolidated investments in power plants | — |
| | — |
| | (12 | ) | | — |
| | — |
| | (12 | ) | Income (loss) from operations | 338 |
|
| (24 | ) |
| 298 |
|
| (11 | ) |
| 3 |
| | 604 |
| Interest expense, net of interest income | | | | | | | | | | | 568 |
| Loss on interest rate derivatives | | | | | | | | | | | 149 |
| Debt extinguishment costs and other (income) expense, net | | | | | | | | | | | 108 |
| Loss before income taxes | | | | | | | | | | | $ | (221 | ) |
_________ | | (1) | Our North segment includes Commodity Margin related to Riverside Energy Center, LLC of $32 million and $31 million for the three months ended September 30, 2012 and 2011, respectively, and $64 million and $62 million for the nine months ended September 30, 2012 and 2011, respectively. |
| | (2) | Mark-to-market commodity activity represents the change in the unrealized portion of our mark-to-market activity, net, included in operating revenues and fuel and purchased energy expense on our Consolidated Condensed Statements of Operations. |
| | (3) | Includes $16 million and $11 million of lease levelization for the three months ended September 30, 2012 and 2011, respectively, and $4 million of amortization expense for each of the three months ended September 30, 2012 and 2011. |
| | (4) | Excludes $4 million and $3 million of RGGI compliance and other environmental costs for the three months ended September 30, 2012 and 2011, respectively, and $9 million and $7 million for the nine months ended September 30, 2012 and 2011, respectively, which are components of Commodity Margin. |
| | (5) | Includes $7 million and $15 million of lease levelization and $11 million and $5 million of amortization expense for the nine months ended September 30, 2012 and 2011, respectively. |
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