| Schedule of Net (Loss) Income Per Unit [Text Block] |
The following table details the calculation of net (loss) income per common unit: | | | | | | | | | | | | | | Year Ended December 31, | | 2019 | | 2018 | | 2017 | | (Thousands of Dollars, Except Unit and Per Unit Data) | Net (loss) income | $ | (105,693 | ) | | $ | 205,794 |
| | $ | 147,964 |
| Distributions to preferred limited partners | (121,693 | ) | | (92,540 | ) | | (40,448 | ) | Distributions to general partner (including incentive distribution rights) | — |
| | (1,141 | ) | | (54,921 | ) | Distributions to common limited partners | (259,136 | ) | | (248,705 | ) | | (407,681 | ) | Distribution equivalent rights to restricted units | (2,659 | ) | | (2,045 | ) | | (2,965 | ) | Distributions in excess of (loss) income | $ | (489,181 | ) | | $ | (138,637 | ) | | $ | (358,051 | ) | | | | | | | Distributions to common limited partners | $ | 259,136 |
| | $ | 248,705 |
| | $ | 407,681 |
| Allocation of distributions in excess of (loss) income | (489,181 | ) | | (138,659 | ) | | (350,890 | ) | Series D Preferred Unit accretion (refer to Note 19) | (18,085 | ) | | (8,195 | ) | | — |
| Loss to common unitholders attributable to the Merger (refer to Note 4) | — |
| | (377,079 | ) | | — |
| Net (loss) income attributable to common units | $ | (248,130 | ) | | $ | (275,228 | ) | | $ | 56,791 |
| | | | | | | Basic weighted-average common units outstanding | 107,789,030 |
| | 99,490,495 |
| | 88,825,964 |
| | | | | | | Diluted common units outstanding: | | | | | | Basic weighted-average common units outstanding | 107,789,030 |
| | 99,490,495 |
| | 88,825,964 |
| Effect of dilutive potential common units | 65,669 |
| | 40,677 |
| | — |
| Diluted weighted-average common units outstanding | 107,854,699 |
| | 99,531,172 |
| | 88,825,964 |
| | | | | | | Basic and diluted net (loss) income per common unit | $ | (2.30 | ) | | $ | (2.77 | ) | | $ | 0.64 |
|
|