CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016
Operating activities:
Net income from continuing operations	[1]	$ 411.3	$ 443.4
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization		217.1	206.3
Derivative fair value net (gains) losses		(0.8)	10.2
Environmental costs, net of recoveries		14.2	15.7
Equity earnings from investments in joint ventures		(6.4)	0.0
Gain on sale of assets		(62.1)	0.0
Allowance for equity used during construction	[1]	(21.0)	(25.6)
Amortization of debt issuance and hedging costs		18.6	20.0
Asset impairment		0.0	0.4
Other		(2.4)	5.4
Changes in operating assets and liabilities		(353.7)	(232.1)
Net cash provided by operating activities		214.8	443.7
Net cash (used in) provided by discontinued operations		(171.1)	102.8
Investing activities:
Capital expenditures		(228.9)	(637.9)
Changes in restricted cash		13.6	11.1
Proceeds from the sale of net assets		314.0	0.0
Proceeds from the sale of Midcoast assets		1,310.0	0.0
Investments in joint ventures		(1,556.7)	0.0
Other		(2.5)	(2.3)
Net cash used in investing activities		(150.5)	(629.1)
Net cash used in discontinued operations		(14.0)	(31.0)
Financing activities:
Redemption of Series 1 preferred units		(1,200.0)	0.0
Payment of Series 1 preferred unit dividends		(357.3)	0.0
Net proceeds from Class A unit issuances		1,224.5	0.0
Distributions to partners		(345.7)	(399.0)
Repayments to General Partner and affiliates		(1,829.4)	0.0
Borrowings from General Partner and affiliates		1,500.0	0.0
Net (repayments) borrowings under credit facilities		(865.0)	630.0
Net commercial paper borrowings (repayments)		675.7	(131.8)
Acquisition of noncontrolling interest in subsidiary		(360.3)	0.0
Sale of noncontrolling interest in subsidiary		450.1	0.0
Contributions from noncontrolling interests		1,285.0	81.9
Distributions to noncontrolling interests		(219.0)	0.0
Other		(0.5)	(0.8)
Net cash (used in) provided by financing activities		(41.9)	180.3
Net cash (used in) provided by discontinued operations		229.0	(81.7)
Net increase (decrease) in cash and cash equivalents		66.3	(15.0)
Cash disposed as part of the Midcoast sale		(51.3)	0.0
Cash and cash equivalents at beginning of year - continuing operations		101.3	130.1
Cash and cash equivalents at beginning of year - discontinued operations		7.4	18.0
Cash and cash equivalents at end of period		123.7	133.1
Cash and cash equivalents at end of period - continuing operations		123.7	125.0
Cash and cash equivalents at end of period - discontinued operations		$ 0.0	$ 8.1

[1] Certain costs that are not allocated to individual segments, including Other, interest expense, allowance for equity used during construction, and income taxes are included in the consolidated total.