Unaudited Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
CURRENT ASSETS:
Cash and cash equivalents	$ 16,092	$ 9,041
Accounts receivable - trade, net	419,903	495,449
Inventories	95,667	88,653
Other	48,432	42,890
Total current assets	580,094	636,033
FIXED ASSETS, at cost	5,652,880	5,601,015
Less: Accumulated depreciation	(802,261)	(734,986)
Net fixed assets	4,850,619	4,866,029
MINERAL LEASEHOLDS, net of accumulated depletion	563,369	564,506
NET INVESTMENT IN DIRECT FINANCING LEASES, net of unearned income	123,270	125,283
EQUITY INVESTEES	372,493	381,550
INTANGIBLE ASSETS, net of amortization	178,755	182,406
GOODWILL	325,046	325,046
OTHER ASSETS, net of amortization	116,190	56,628
TOTAL ASSETS	7,109,836	7,137,481
CURRENT LIABILITIES:
Accounts payable - trade	263,527	270,855
Accrued liabilities	152,163	185,409
Total current liabilities	415,690	456,264
SENIOR SECURED CREDIT FACILITY	1,279,000	1,099,200
SENIOR UNSECURED NOTES, net of debt issuance costs	2,456,749	2,598,918
DEFERRED TAX LIABILITIES	12,138	11,913
OTHER LONG-TERM LIABILITIES	290,401	256,571
Total liabilities	4,453,978	4,422,866
MEZZANINE CAPITAL:
Class A Convertible Preferred Units, 22,901,980 and 22,411,728 issued and outstanding at March 31, 2018 and December 31, 2017, respectively	712,687	697,151
PARTNERS’ CAPITAL:
Common unitholders, 122,579,218 and 122,579,218 units issued and outstanding at March 31, 2018 and December 31, 2017, respectively	1,951,590	2,026,147
Accumulated other comprehensive loss	(604)	(604)
Noncontrolling interests	(7,815)	(8,079)
Total partners' capital	1,943,171	2,017,464
TOTAL LIABILITIES, MEZZANINE CAPITAL AND PARTNERS’ CAPITAL	$ 7,109,836	$ 7,137,481