| In millions, except per share items | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 | Dec-31-13 | Dec-31-12 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Cash flows from operating activities: | | | | | | | | |
| Net income | 162.1 | 671.3 | 610.4 | 538.0 | | | | |
| Adjustments to reconcile net income to net cash from operating activities: | | | | | | | | |
| Depreciation | 223.2 | 171.9 | 107.2 | 62.7 | | | | |
| Amortization of intangible assets | 53.3 | 41.5 | 5.5 | | | | | |
| Impairments of long-lived assets | | | | | | | | |
| Equity income | -163.3 | -61.8 | -22.2 | -9.9 | -2.4 | | | |
| AFUDC – equity | -5.2 | -5.6 | -5.1 | -19.4 | -6.3 | -3.3 | -1.2 | -8.2 |
| Non-cash long-term compensation expense | 0.3 | 1.3 | 0.2 | 0.2 | 1.5 | 3.4 | 1.0 | 2.3 |
| Changes in other assets and liabilities: | | | | | | | | |
| Accounts receivable | 17.1 | -48.0 | -24.6 | -9.0 | -0.6 | -5.4 | -4.7 | -10.8 |
| Accounts payable | -89.2 | 95.0 | 2.9 | -37.9 | 8.5 | 4.7 | -4.5 | -4.9 |
| Other assets and other liabilities | -3.1 | 59.6 | 7.6 | 4.5 | 6.1 | 7.3 | 0.5 | -5.4 |
| Net cash provided by operating activities | 1,049.4 | 1,187.2 | 681.8 | 537.9 | 489.7 | 324.8 | 260.3 | 173.0 |
| |
| Cash flows from investing activities: | | | | | | | | |
| Capital expenditures | -1,022.5 | -837.0 | -380.2 | -584.8 | -458.1 | -356.2 | -283.0 | -214.9 |
| Capital contributions to the MVP Joint Venture | | -11.3 | | -98.4 | | | | |
| Principal payments received on the Preferred Interest | 4.7 | 4.4 | 4.2 | 1.0 | | | | |
| Net cash used in investing activities | -2,629.6 | -2,950.3 | -535.5 | -732.0 | -1,043.8 | -524.4 | -283.0 | -214.9 |
| |
| Cash flows from financing activities: | | | | | | | | |
| Proceeds from revolving credit facility borrowings | 2,402.0 | 3,427.5 | 544.0 | 740.0 | 617.0 | 450.0 | | |
| Payments on revolving credit facility borrowings | -2,397.0 | -3,268.5 | -344.0 | -1,039.0 | -318.0 | -450.0 | | |
| Distributions paid to common unitholders | -905.9 | -736.1 | -442.2 | -329.5 | -212.3 | -119.6 | -97.6 | -22.6 |
| Distributions paid to Series A Preferred unitholders | -48.5 | | | | | | | |
| Net cash provided by financing activities | 1,578.5 | 1,725.9 | -205.0 | -106.5 | 779.5 | 316.9 | -9.0 | 91.9 |
| |
| Cash paid during the period for: | | | | | | | | |
| Interest, net of amount capitalized | 216.6 | 54.2 | 43.8 | 13.9 | 19.6 | 1.6 | 0.9 | 6.5 |