CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net income	$ 88,971	$ 101,247
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	32,173	27,581
Gain on reserve swap	(8,149)
Equity and other unconsolidated investment income, net	(14,930)
Distributions of earnings from unconsolidated investments	16,162
Non-cash interest charge, net	555	300
Gain on sale of assets	(150)	(4,108)
Asset impairment	734
Change in operating assets and liabilities:
Accounts receivable	4,250	5,851
Other assets	(2,985)	24
Accounts payable and accrued liabilities	221	562
Accrued interest	(576)	(158)
Deferred revenue	9,951	6,551
Accrued incentive plan expenses	(1,219)	(5,261)
Property, franchise and other taxes payable	(1,359)	(582)
Net cash provided by operating activities	123,649	132,007
Cash flows from investing activities:
Acquisition of land and mineral rights		(94,453)
Acquisition or construction of plant and equipment		(492)
Acquisition of equity interests	(292,979)
Distributions from unconsolidated investments	10,777
Proceeds from sale of assets	154	285
Return on direct financing lease and contractual override	555	904
Investment in direct financing lease		(59,009)
Net cash used in investing activities	(281,493)	(152,765)
Cash flows from financing activities:
Proceeds from loans	243,000	73,000
Repayment of loans	(79,538)	(23,108)
Deferred financing costs	(1,621)
Proceeds from issuance of units	75,000
Capital contribution by general partner	1,531
Costs associated with equity transactions	(60)
Repayment of obligation related to acquisitions		(500)
Distributions to partners	(124,688)	(121,582)
Net cash provided by (used in) financing activities	113,624	(72,190)
Net (decrease) in cash and cash equivalents	(44,220)	(92,948)
Cash and cash equivalents at beginning of period	149,424	214,922
Cash and cash equivalents at end of period	105,204	121,974
Supplemental cash flow information:
Cash paid during the period for interest	$ 29,085	$ 26,976