CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash provided by operating activities:
Net income (loss)	$ (41.3)	$ 454.3	$ 740.0
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	580.9	536.2	458.2
Derivative fair value net (gains) losses (Note 21)	127.3	(25.1)	(72.0)
Inventory market price adjustments (Note 9)	0.0	5.8	11.4
Asset impairment (Note 11)	767.7	74.8	15.6
Environmental costs, net of recoveries (Note 25)	9.7	5.6	82.2
Distributions from investments in joint ventures	30.0	29.2	12.2
Equity earnings from investments in joint ventures	(30.0)	(29.2)	(13.2)
Goodwill impairment (Note 15)	0.0	246.7	0.0
Allowance for equity used during construction	(45.5)	(70.3)	(57.2)
Amortization of debt issuance and hedging costs	40.2	17.7	9.4
Other	1.6	5.9	15.1
Settlement of interest rate derivatives (Note 21)	0.0	(238.3)	(0.4)
Changes in operating assets and liabilities (Note 23)	(24.9)	17.5	(384.5)
Net cash provided by operating activities	1,415.7	1,030.8	816.8
Cash used in investing activities:
Additions to property, plant and equipment (Note 23)	(1,091.3)	(2,116.8)	(2,933.6)
Changes in restricted cash	10.1	65.4	(27.6)
Asset acquisitions	0.0	(85.0)	(0.2)
Proceeds from the sale of net assets	15.2	6.6	0.0
Investment in joint venture	(0.3)	(4.2)	(36.7)
Distributions from investments in joint ventures in excess of cumulative earnings	11.3	12.0	27.8
Other	(11.3)	(4.4)	(6.3)
Net cash used in investing activities	(1,066.3)	(2,126.4)	(2,976.6)
Cash provided by (used in) financing activities:
Net proceeds from unit issuances (Note 20)	0.0	294.8	0.0
Distributions to partners (Note 20)	(864.2)	(835.9)	(727.9)
Repayments to General Partner	0.0	(306.0)	(12.0)
Proceeds from issuance of debt, net of discounts (Note 17)	0.0	1,600.0	398.1
Repayments of debt (Note 17)	(300.0)	0.0	(200.0)
Net borrowings under credit facilities (Note 17)	85.0	80.0	1,185.0
Net commercial paper borrowings (repayments) (Note 17)	65.8	(286.1)	312.1
Debt issuance costs	(0.8)	(24.9)	0.0
Borrowings from General Partner and affiliates	750.0	0.0	0.0
Distributions to noncontrolling interest (Note 24)	(241.8)	(339.4)	(154.0)
Net cash provided by (used in) financing activities	(388.7)	1,045.8	2,192.9
Contribution from noncontrolling interest (Note 24)	117.3	863.3	1,391.6
Net increase (decrease) in cash and cash equivalents	(39.3)	(49.8)	33.1
Cash and cash equivalents at beginning of year	148.1	197.9	164.8
Cash and cash equivalents at end of period	$ 108.8	$ 148.1	$ 197.9