| Schedule of Segment Reporting Information [Table Text Block] |
Segment information and Corporate activities included in the accompanying Condensed Consolidated Statements of Income (Loss) were as follows (in thousands): | | | | | | | | | | | | | | Three Months Ended June 30, 2013 | | External Operating Revenue | | Intercompany Operating Revenue | | Income (Loss) from Continuing Operations | Utilities: | | | | | | | Electric | | $ | 154,338 |
| | $ | 3,694 |
| | $ | 10,610 |
| Gas | | 105,836 |
| | — |
| | 3,192 |
| Non-regulated Energy: | | | | | | | Power Generation | | 1,031 |
| | 19,094 |
| | 5,031 |
| Coal Mining | | 6,807 |
| | 7,511 |
| | 1,973 |
| Oil and Gas | | 11,814 |
| | — |
| | (1,964 | ) | Corporate activities (a) | | — |
| | — |
| | 11,679 |
| Intercompany eliminations | | — |
| | (30,299 | ) | | (3 | ) | Total | | $ | 279,826 |
| | $ | — |
| | $ | 30,518 |
|
| | | | | | | | | | | | | | Three Months Ended June 30, 2012 | | External Operating Revenue | | Intercompany Operating Revenue | | Income (Loss) from Continuing Operations | Utilities: | | | | | | | Electric | | $ | 144,560 |
| | $ | 5,174 |
| | $ | 14,159 |
| Gas | | 70,386 |
| | — |
| | 1,159 |
| Non-regulated Energy: | | | | | | | Power Generation | | 759 |
| | 17,975 |
| | 3,926 |
| Coal Mining | | 6,037 |
| | 7,090 |
| | 1,234 |
| Oil and Gas (b) | | 20,621 |
| | — |
| | (19,621 | ) | Corporate activities (a) | | — |
| | — |
| | (13,180 | ) | Intercompany eliminations | | — |
| | (30,239 | ) | | — |
| Total | | $ | 242,363 |
| | $ | — |
| | $ | (12,323 | ) |
| | | | | | | | | | | | | | Six Months Ended June 30, 2013 | | External Operating Revenues | | Intercompany Operating Revenues | | Income (Loss) from Continuing Operations | Utilities: | | | | | | | Electric | | $ | 312,821 |
| | $ | 7,841 |
| | $ | 22,966 |
| Gas | | 305,648 |
| | — |
| | 21,675 |
| Non-regulated Energy: | | | | | | | Power Generation | | 2,053 |
| | 38,432 |
| | 10,675 |
| Coal Mining | | 12,817 |
| | 15,084 |
| | 3,038 |
| Oil and Gas | | 27,158 |
| | — |
| | (2,017 | ) | Corporate (a) | | — |
| | — |
| | 17,378 |
| Intercompany eliminations | | — |
| | (61,357 | ) | | — |
| Total | | $ | 660,497 |
| | $ | — |
| | $ | 73,715 |
|
| | | | | | | | | | | | | | Six Months Ended June 30, 2012 | | External Operating Revenues | | Intercompany Operating Revenues | | Income (Loss) from Continuing Operations | Utilities: | | | | | | | Electric | | $ | 300,693 |
| | $ | 8,210 |
| | $ | 22,905 |
| Gas | | 250,908 |
| | — |
| | 16,366 |
| Non-regulated Energy: | | | | | | | Power Generation | | 1,937 |
| | 36,424 |
| | 10,840 |
| Coal Mining | | 12,410 |
| | 15,706 |
| | 2,234 |
| Oil and Gas (b) | | 42,266 |
| | — |
| | (19,608 | ) | Corporate (a)(c) | | — |
| | — |
| | (9,789 | ) | Intercompany eliminations | | — |
| | (60,340 | ) | | — |
| Total | | $ | 608,214 |
| | $ | — |
| | $ | 22,948 |
|
__________ | | (a) | Income (loss) from continuing operations includes a $12.2 million and a $17.1 million net after-tax non-cash mark-to-market gain on certain interest rate swaps for the three and six months ended June 30, 2013, respectively, and a $10.1 million and a $2.3 million net after-tax non-cash mark-to-market loss for the three and six months ended June 30, 2012, respectively, for those same interest rate swaps. |
| | (b) | Income (loss) from continuing operations includes a $17.3 million non-cash after-tax ceiling test impairment charge. See Note 14 for further information. |
| | (c) | Certain indirect corporate costs and inter-segment interest expense after-tax totaling $1.6 million for the six months ended June 30, 2012, were included in the Corporate activities in continuing operations and were not reclassified as discontinued operations. |
Segment information and Corporate balances included in the accompanying Condensed Consolidated Balance Sheets were as follows (in thousands): | | | | | | | | | | | | | Total Assets (net of inter-company eliminations) as of: | June 30, 2013 | | Dec. 31, 2012 | | June 30, 2012 | Utilities: | | | | | | Electric (a) | $ | 2,417,952 |
| | $ | 2,387,458 |
| | $ | 2,300,948 |
| Gas | 734,337 |
| | 765,165 |
| | 684,545 |
| Non-regulated Energy: | | | | | | Power Generation (a) | 108,515 |
| | 119,170 |
| | 122,856 |
| Coal Mining | 82,553 |
| | 83,810 |
| | 90,021 |
| Oil and Gas | 256,855 |
| | 258,460 |
| | 416,617 |
| Corporate activities | 146,302 |
| | 115,408 |
| | 159,293 |
| Total assets | $ | 3,746,514 |
| | $ | 3,729,471 |
| | $ | 3,774,280 |
|
__________ | | (a) | The PPA pertaining to the portion of the Pueblo Airport Generation Station owned by Colorado IPP that supports Colorado customers is accounted for as a capital lease. Therefore, assets owned by the Power Generation segment are included in Total assets of Electric Utilities Segment under this accounting for a capital lease. |
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