| Schedule of Quarterly Financial Information [Table Text Block] |
| | | | | | | | | | | | | | | | | | | | | | First Quarter | | Second Quarter | | Third Quarter | | Fourth Quarter | | Total | | (Thousands of Dollars, Except Per Unit Data) | 2013: | | | | | | | | | | Revenues | $ | 998,186 |
| | $ | 902,014 |
| | $ | 778,145 |
| | $ | 785,387 |
| | $ | 3,463,732 |
| Operating income (loss) | $ | 63,358 |
| | $ | 76,972 |
| | $ | 68,751 |
| | $ | (228,202 | ) | | $ | (19,121 | ) | Income (loss) from continuing operations | $ | 19,599 |
| | $ | 34,712 |
| | $ | 35,682 |
| | $ | (275,502 | ) | | $ | (185,509 | ) | Income (loss) from discontinued operations, net of tax | 4,805 |
| | (1,743 | ) | | (2,446 | ) | | (99,778 | ) | | (99,162 | ) | Net income (loss) | $ | 24,404 |
| | $ | 32,969 |
| | $ | 33,236 |
| | $ | (375,280 | ) | | $ | (284,671 | ) | Net income (loss) per unit applicable to limited partners: | | | | | | | | | | Continuing operations | $ | 0.10 |
| | $ | 0.30 |
| | $ | 0.31 |
| | $ | (3.60 | ) | | $ | (2.89 | ) | Discontinued operations | 0.07 |
| | (0.02 | ) | | (0.03 | ) | | (1.13 | ) | | (1.11 | ) | Total | $ | 0.17 |
| | $ | 0.28 |
| | $ | 0.28 |
| | $ | (4.73 | ) | | $ | (4.00 | ) | Cash distributions per unit applicable to limited partners | $ | 1.095 |
| | $ | 1.095 |
| | $ | 1.095 |
| | $ | 1.095 |
| | $ | 4.380 |
| | | | | | | | | | | 2012: | | | | | | | | | | Revenues | $ | 1,606,449 |
| | $ | 1,764,667 |
| | $ | 1,591,730 |
| | $ | 982,890 |
| | $ | 5,945,736 |
| Operating income (loss) | $ | 60,882 |
| | $ | (201,925 | ) | | $ | 62,750 |
| | $ | 60,125 |
| | $ | (18,168 | ) | Income (loss) from continuing operations | $ | 39,978 |
| | $ | (241,871 | ) | | $ | 17,000 |
| | $ | 18,892 |
| | $ | (166,001 | ) | Loss from discontinued operations, net of tax | (13,724 | ) | | (4,939 | ) | | (12,658 | ) | | (29,915 | ) | | (61,236 | ) | Net income (loss) | $ | 26,254 |
| | $ | (246,810 | ) | | $ | 4,342 |
| | $ | (11,023 | ) | | $ | (227,237 | ) | Net income (loss) per unit applicable to limited partners: | | | | | | | | | | Continuing operations | $ | 0.41 |
| | $ | (3.48 | ) | | $ | 0.08 |
| | $ | 0.10 |
| | $ | (2.79 | ) | Discontinued operations | (0.18 | ) | | (0.08 | ) | | (0.17 | ) | | (0.37 | ) | | (0.82 | ) | Total | $ | 0.23 |
| | $ | (3.56 | ) | | $ | (0.09 | ) | | $ | (0.27 | ) | | $ | (3.61 | ) | Cash distributions per unit applicable to limited partners | $ | 1.095 |
| | $ | 1.095 |
| | $ | 1.095 |
| | $ | 1.095 |
| | $ | 4.380 |
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