UNAUDITED CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
CURRENT ASSETS:
Cash and cash equivalents	$ 18,449	$ 21,282
Restricted cash	15,338	5,736
Accounts receivable - trade, net	473,929	392,465
Inventories	72,427	99,877
Other	64,000	60,809
Total current assets	644,143	580,169
FIXED ASSETS, at cost	5,206,508	5,173,475
Less: Accumulated depreciation	(1,381,384)	(1,322,141)
Net fixed assets	3,825,124	3,851,334
MINERAL LEASEHOLDS, net of accumulated depletion	551,663	552,575
EQUITY INVESTEES	310,024	319,068
INTANGIBLE ASSETS, net of amortization	127,848	128,742
GOODWILL	301,959	301,959
RIGHT OF USE ASSETS, net	149,711	153,925
OTHER ASSETS, net of amortization	39,141	45,847
TOTAL ASSETS	5,949,613	5,933,619
CURRENT LIABILITIES:
Accounts payable - trade	257,728	198,433
Accrued liabilities	196,366	184,978
Total current liabilities	454,094	383,411
SENIOR SECURED CREDIT FACILITY	699,000	643,700
SENIOR UNSECURED NOTES, net of debt issuance costs	2,671,262	2,750,016
DEFERRED TAX LIABILITIES	13,389	13,317
OTHER LONG-TERM LIABILITIES	410,189	393,018
Total liabilities	4,247,934	4,183,462
MEZZANINE CAPITAL:
Class A Convertible Preferred Units, 25,336,778 issued and outstanding at March 31, 2021 and December 31, 2020	790,115	790,115
Redeemable noncontrolling interests, 161,209 and 141,249 preferred units issued and outstanding at March 31, 2021 and December 31, 2020, respectively	163,655	141,194
PARTNERS’ CAPITAL:
Common unitholders, 122,579,218 units issued and outstanding at March 31, 2021 and December 31, 2020	758,031	829,326
Accumulated other comprehensive loss	(9,243)	(9,365)
Noncontrolling interests	(879)	(1,113)
Total partners' capital	747,909	818,848
TOTAL LIABILITIES, MEZZANINE CAPITAL AND PARTNERS’ CAPITAL	$ 5,949,613	$ 5,933,619