Unaudited Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
CURRENT ASSETS:
Cash and cash equivalents	$ 7,846	$ 9,041
Accounts receivable - trade, net	432,777	495,449
Inventories	92,520	88,653
Other	42,526	42,890
Total current assets	575,669	636,033
FIXED ASSETS, at cost	5,686,153	5,601,015
Less: Accumulated depreciation	(867,465)	(734,986)
Net fixed assets	4,818,688	4,866,029
MINERAL LEASEHOLDS, net of accumulated depletion	562,315	564,506
NET INVESTMENT IN DIRECT FINANCING LEASES, net of unearned income	121,207	125,283
EQUITY INVESTEES	362,852	381,550
INTANGIBLE ASSETS, net of amortization	173,685	182,406
GOODWILL	325,046	325,046
OTHER ASSETS, net of amortization	118,170	56,628
TOTAL ASSETS	7,057,632	7,137,481
CURRENT LIABILITIES:
Accounts payable - trade	239,212	270,855
Accrued liabilities	144,947	185,409
Total current liabilities	384,159	456,264
SENIOR SECURED CREDIT FACILITY	1,306,300	1,099,200
SENIOR UNSECURED NOTES, net of debt issuance costs	2,458,614	2,598,918
DEFERRED TAX LIABILITIES	12,244	11,913
OTHER LONG-TERM LIABILITIES	293,524	256,571
Total liabilities	4,454,841	4,422,866
MEZZANINE CAPITAL:
Class A Convertible Preferred Units, 23,402,956 and 22,411,728 issued and outstanding at June 30, 2018 and December 31, 2017, respectively	728,459	697,151
PARTNERS’ CAPITAL:
Common unitholders, 122,579,218 and 122,579,218 units issued and outstanding at June 30, 2018 and December 31, 2017, respectively	1,881,957	2,026,147
Accumulated other comprehensive loss	(604)	(604)
Noncontrolling interests	(7,021)	(8,079)
Total partners' capital	1,874,332	2,017,464
TOTAL LIABILITIES, MEZZANINE CAPITAL AND PARTNERS’ CAPITAL	$ 7,057,632	$ 7,137,481