| Schedule of Segment Reporting Information, by Segment [Table Text Block] |
Results of operations for the reportable segments were as follows: | | | | | | | | | | | | | | | | | | | | | | | | | | Three Months Ended September 30, | | Nine Months Ended September 30, | | | 2021 | | 2020 | | 2021 | | 2020 | | | (Thousands of Dollars) | | Revenues: | | | | | | | | | | | | | | | | | Pipeline | $ | 196,207 | | | $ | 176,210 | | | $ | 558,341 | | | $ | 537,999 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Storage | 108,142 | | | 122,435 | | | 335,964 | | | 365,059 | | | | | | | | | | | Fuels marketing | 107,996 | | | 63,946 | | | 306,790 | | | 191,873 | | | | | | | | | | | | | | | | | | | | | | | | | | | Consolidation and intersegment eliminations | — | | | — | | | (11) | | | (9) | | | Total revenues | $ | 412,345 | | | $ | 362,591 | | | $ | 1,201,084 | | | $ | 1,094,922 | | | | | | | | | | | Operating income (loss): | | | | | | | | | Pipeline | $ | 40,201 | | | $ | 83,821 | | | $ | 216,092 | | | $ | 32,878 | | | Storage | (91,089) | | | 48,816 | | | (2,186) | | | 140,637 | | | Fuels marketing | 949 | | | (31) | | | 5,978 | | | 9,761 | | | | | | | | | | | Total segment operating (loss) income | (49,939) | | | 132,606 | | | 219,884 | | | 183,276 | | | General and administrative expenses | 27,365 | | | 25,457 | | | 79,334 | | | 72,128 | | | Other depreciation and amortization expense | 1,881 | | | 2,105 | | | 5,841 | | | 6,462 | | | Total operating (loss) income | $ | (79,185) | | | $ | 105,044 | | | $ | 134,709 | | | $ | 104,686 | |
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| Reconciliation of Assets from Segment to Consolidated [Table Text Block] |
Total assets by reportable segment were as follows: | | | | | | | | | | | | | September 30, 2021 | | December 31, 2020 | | | (Thousands of Dollars) | | Pipeline | $ | 3,460,180 | | | $ | 3,609,508 | | | Storage | 1,779,029 | | | 1,897,167 | | | Fuels marketing | 42,261 | | | 31,967 | | | Total segment assets | 5,281,470 | | | 5,538,642 | | | Other partnership assets | 124,267 | | | 278,376 | | | Total consolidated assets | $ | 5,405,737 | | | $ | 5,817,018 | |
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