CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income (loss)	$ 100,066	$ (11,792)	$ 82,079
Adjustments to reconcile net income to net cash provided by operating activities -
Depreciation, depletion and amortization	319,806	313,190	252,480
Provision for leased items no longer in use	0	0	12,589
Gain on sale of assets	0	(42,264)	(40,311)
Impairment expense	0	126,282	0
Amortization and write-off of debt issuance costs and premium or discount	10,766	12,165	13,103
Amortization of unearned income and initial direct costs on direct financing leases	(12,247)	(13,035)	(13,747)
Payments received under direct financing leases	20,668	20,668	20,668
Equity in earnings of investments in equity investees	(56,484)	(43,626)	(51,046)
Cash distributions of earnings of equity investees	56,081	42,735	47,316
Non-cash effect of long-term incentive compensation plans	8,496	3,941	(5,775)
Deferred and other tax benefits	65	663	(4,060)
Unrealized (gains) losses on derivative transactions	12,586	(11,795)	10,943
Other, net	(6,418)	(4,941)	(10,839)
Net changes in components of operating assets and liabilities, net of acquisitions (See Note 16)	(71,098)	(2,152)	10,156
Net cash provided by operating activities	382,287	390,039	323,556
CASH FLOWS FROM INVESTING ACTIVITIES:
Payments to acquire fixed and intangible assets	(163,248)	(195,367)	(250,593)
Cash distributions received from equity investees—return of investment	21,250	28,979	35,582
Investments in equity investees	0	(3,018)	(4,647)
Acquisitions	0	0	(1,325,759)
Contributions in aid of construction costs	0	0	124
Proceeds from asset sales	1,187	310,099	85,722
Net cash used in (provided by) investing activities	(140,811)	140,693	(1,459,571)
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings on senior secured credit facility	815,100	980,700	1,458,700
Repayments on senior secured credit facility	(825,900)	(1,109,800)	(1,637,700)
Proceeds from issuance of senior unsecured notes	0	0	1,000,000
Net proceeds from issuance of preferred units (Note 12)	122,900	0	726,419
Repayment of senior unsecured notes	0	(145,170)	(204,830)
Debt issuance costs	0	(242)	(25,913)
Issuance of common units for cash, net	0	0	140,513
Contributions from noncontrolling interests	5,652	2,592	2,770
Distributions to Class A Convertible Preferred unitholders	(43,506)	0	0
Distributions to common unitholders	(269,674)	(257,416)	(321,875)
Other, net	57	(137)	(57)
Net cash provided by (used in) financing activities	(195,371)	(529,473)	1,138,027
Net increase in cash and cash equivalents and restricted cash	46,105	1,259	2,012
Cash and cash equivalents and restricted cash at beginning of period	10,300	9,041	7,029
Cash and cash equivalents and restricted cash at end of period	$ 56,405	$ 10,300	$ 9,041