CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities
Net income	$ 607.7	$ 620.6	$ 617.8
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation expense	192.5	181.3	165.6
Income from equity investments	(7.7)	(5.3)	(10.6)
Distributions from equity investments	11.4	13.0	17.4
Amortization of deferred financing costs	8.4	8.8	7.3
Equity-based compensation expense	1.7	1.6	1.4
Deferred income tax expense	37.9	26.6	14.6
Changes in assets and liabilities:
Accounts receivable - trade	(1.6)
Accounts receivable – affiliate	0.6	(2.6)	(27.0)
Other current and noncurrent assets	(0.2)	3.5	(5.1)
Accounts payable – trade	3.5	8.1	(3.1)
Accounts payable – affiliate	10.1	(5.8)	9.7
Accrued liabilities	4.0	9.1	9.2
Other current and noncurrent liabilities	(1.9)	2.2	(1.7)
Net cash provided by operating activities	866.4	861.1	795.5
Cash flows from investing activities
Additions to property, plant and equipment	(223.5)	(238.2)	(163.2)
Net cash used in investing activities	(223.5)	(238.2)	(163.2)
Cash flows from financing activities
Net proceeds from (repayments of) bank borrowings with maturities of 90 days or less	322.0	(86.0)	(80.0)
Bank borrowings with maturities of greater than 90 days
Borrowings		20.0
Repayments	(2.5)	(10.0)	(10.0)
Proceeds from issuance of senior notes		400.0	750.0
Deferred financing costs		(13.3)	(11.6)
Transaction costs	(3.1)	(1.5)	(2.1)
Class B unit repurchase	(400.0)	(400.0)	(750.0)
Distributions to shareholders/unitholders	(127.5)	(91.0)	(49.4)
Distributions to noncontrolling interest	(429.5)	(440.2)	(479.6)
Net cash used in financing activities	(640.6)	(622.0)	(632.7)
Increase (decrease) in cash and cash equivalents	2.3	0.9	(0.4)
Cash and cash equivalents, beginning of period	3.1	2.2	2.6
Cash and cash equivalents, end of period	5.4	3.1	2.2
Supplemental disclosure of non-cash investing and financing activities:
(Increase) decrease in accrued capital expenditures and related liabilities	(22.2)	6.5	(19.8)
Recognition of deferred tax asset	$ 185.1	86.4	89.0
Tioga System Acquisition contingent liability adjustment		$ (2.9)	$ (4.1)