| In millions, except per share items | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 | Dec-31-13 |
| | 10-K | 10-K | 10-K | 10-K | 10-K |
| Cash flows from operating activities: | | | | | |
| Net income | 568.9 | 535.0 | 434.0 | 245.9 | 157.9 |
| Adjustments to reconcile net income to net cash from operating activities: | | | | | |
| Equity income | -22.2 | -9.9 | -2.4 | | |
| AFUDC – equity | -5.1 | -19.4 | -6.3 | -3.3 | -1.2 |
| Non-cash long-term compensation expense | 0.5 | 0.4 | 1.5 | 3.4 | 1.0 |
| Changes in other assets and liabilities: | | | | | |
| Accounts receivable | -8.1 | -2.9 | -0.6 | -5.4 | -4.7 |
| Accounts payable | 4.8 | -9.4 | 8.5 | 4.7 | -4.5 |
| Due to/from EQT affiliates | 3.2 | -34.1 | 216.9 | 334.1 | 235.0 |
| Other assets and other liabilities | 8.3 | 4.2 | 6.0 | 7.3 | -0.3 |
| Net cash provided by operating activities | 647.8 | 535.4 | 488.3 | | |
| |
| Cash flows from investing activities: | | | | | |
| Capital expenditures | -301.6 | -584.8 | -458.1 | -356.2 | -283.0 |
| Principal payments received on the Preferred Interest | 4.2 | 1.0 | | | |
| Net cash used in investing activities | -457.0 | -732.0 | -1,043.8 | | |
| |
| Cash flows from financing activities: | | | | | |
| Proceeds from EQM's issuance of long-term debt | | 500.0 | | 500.0 | |
| EQM debt discount and issuance costs | -2.3 | -8.6 | | -9.7 | |
| Capital contributions | 3.1 | 5.9 | 1.7 | 0.4 | 5.6 |
| Net cash provided by (used in) financing activities | -248.5 | -103.8 | 735.7 | | |
| Net change in cash and cash equivalents | -57.6 | -300.5 | 180.2 | -67.3 | -114.7 |
| Cash and cash equivalents at beginning of period | 60.5 | 361.0 | 171.3 | | |
| Cash and cash equivalents at end of period | 2.9 | 60.5 | 361.0 | 171.3 | |
| |
| Cash paid during the period for: | | | | | |
| Interest, net of amount capitalized | 42.0 | 13.9 | 19.6 | 1.6 | 0.9 |
| Non-cash activity during the period for: | | | | | |