UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ (29,435)	$ 28,979
Adjustments to reconcile net income (loss) to net cash provided by operating activities -
Depreciation, depletion and amortization	66,286	74,357
Amortization and write-off of debt issuance costs and discount	3,210	11,527
Amortization of non-cash costs on previously owned direct financing leases	0	(2,929)
Payments received under previously owned direct financing leases (Note 4)	17,500	5,167
Equity in earnings of investments in equity investees	(20,660)	(14,159)
Cash distributions of earnings of equity investees	19,929	13,505
Non-cash effect of long-term incentive compensation plans	1,560	(5,027)
Deferred and other tax liabilities (benefits)	72	(515)
Unrealized (gains) losses on derivative transactions	17,599	(31,118)
Other, net	6,160	2,231
Net changes in components of operating assets and liabilities (Note 14)	(5,062)	7,534
Net cash provided by operating activities	77,159	89,552
CASH FLOWS FROM INVESTING ACTIVITIES:
Payments to acquire fixed and intangible assets	(39,388)	(38,001)
Cash distributions received from equity investees - return of investment	9,314	7,060
Proceeds from asset sales	23	61
Net cash used in investing activities	(30,051)	(30,880)
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings on senior secured credit facility	212,000	393,500
Repayments on senior secured credit facility	(156,700)	(375,400)
Proceeds from issuance of senior unsecured notes due 2028	0	750,000
Proceeds from issuance of preferred units	17,738	0
Repayment of senior unsecured notes	(80,859)	(750,000)
Debt issuance costs	(1,916)	(13,295)
Contributions from noncontrolling interests	236	1,377
Distributions to common unitholders	(18,387)	(67,419)
Distributions to preferred unitholders	(18,684)	(18,684)
Other, net	6,233	6,353
Net cash used in financing activities	(40,339)	(73,568)
Net increase (decrease) in cash, restricted cash, and cash equivalents	6,769	(14,896)
Cash, restricted cash and cash equivalents at beginning of period	27,018	56,405
Cash, restricted cash and cash equivalents at end of period	$ 33,787	$ 41,509