CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net income	$ 20,085	$ 6,939
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation and amortization	36,105	27,921
Long-lived asset impairment	3,484	2,486
Amortization of deferred financing costs	1,030	625
Amortization of debt discount	286	140
Amortization of terminated interest rate swaps	826	935
Interest rate swaps	(136)	64
Unit-based compensation expense	592	756
Provision for doubtful accounts	390	376
Gain on sale of property, plant and equipment	(280)	(673)
Changes in assets and liabilities:
Accounts receivable, trade	3,644	(276)
Other assets and liabilities	12,042	6,110
Net cash provided by operating activities	78,068	45,403
Cash flows from investing activities:
Capital expenditures	(68,239)	(52,950)
Escrow deposit for business acquisition		(17,000)
Proceeds from sale of property, plant and equipment	4,624	1,118
(Increase) decrease in amounts due from affiliates, net	(18,477)	3,738
Net cash used in investing activities	(82,092)	(65,094)
Cash flows from financing activities:
Proceeds from borrowings of long-term debt	140,000	91,000
Repayments of long-term debt	(98,000)	(47,500)
Distributions to unitholders	(35,323)	(28,840)
Payments for debt issuance costs	(1,311)
Payments for settlement of interest rate swaps that include financing elements	(942)	(913)
Purchases of treasury units	(258)	(209)
Capital contribution from limited partners and general partner		6,156
Net cash provided by financing activities	4,166	19,694
Net increase in cash and cash equivalents	142	3
Cash and cash equivalents at beginning of period	295	182
Cash and cash equivalents at end of period	437	185
Supplemental disclosure of non-cash transactions:
Non-cash capital contribution from limited and general partner	2,204	2,592
Contract operations equipment acquired/exchanged, net	$ (5,409)	$ (930)