| Schedule of Segment Reporting Information, by Segment [Table Text Block] |
Results of operations for the reportable segments were as follows: | | | | | | | | | | | | | | | | | | | | | | | | | | Three Months Ended June 30, | | Six Months Ended June 30, | | | 2021 | | 2020 | | 2021 | | 2020 | | | (Thousands of Dollars) | | Revenues: | | | | | | | | | | | | | | | | | Pipeline | $ | 192,906 | | | $ | 166,108 | | | $ | 362,134 | | | $ | 361,789 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Storage | 119,248 | | | 119,407 | | | 227,822 | | | 242,624 | | | | | | | | | | | Fuels marketing | 114,939 | | | 54,025 | | | 198,794 | | | 127,927 | | | | | | | | | | | | | | | | | | | | | | | | | | | Consolidation and intersegment eliminations | — | | | — | | | (11) | | | (9) | | | Total revenues | $ | 427,093 | | | $ | 339,540 | | | $ | 788,739 | | | $ | 732,331 | | | | | | | | | | | Operating income (loss): | | | | | | | | | Pipeline | $ | 96,512 | | | $ | 71,981 | | | $ | 175,891 | | | $ | (50,943) | | | Storage | 46,185 | | | 43,242 | | | 88,903 | | | 91,821 | | | Fuels marketing | 2,298 | | | 3,349 | | | 5,029 | | | 9,792 | | | | | | | | | | | Total segment operating income | 144,995 | | | 118,572 | | | 269,823 | | | 50,670 | | | General and administrative expenses | 27,477 | | | 23,700 | | | 51,969 | | | 46,671 | | | Other depreciation and amortization expense | 1,913 | | | 2,171 | | | 3,960 | | | 4,357 | | | Total operating income (loss) | $ | 115,605 | | | $ | 92,701 | | | $ | 213,894 | | | $ | (358) | |
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| Reconciliation of Assets from Segment to Consolidated [Table Text Block] |
Total assets by reportable segment were as follows: | | | | | | | | | | | | | June 30, 2021 | | December 31, 2020 | | | (Thousands of Dollars) | | Pipeline | $ | 3,540,298 | | | $ | 3,609,508 | | | Storage | 1,918,515 | | | 1,897,167 | | | Fuels marketing | 43,537 | | | 31,967 | | | Total segment assets | 5,502,350 | | | 5,538,642 | | | | | | | Other partnership assets | 143,630 | | | 278,376 | | | Total consolidated assets | $ | 5,645,980 | | | $ | 5,817,018 | |
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