Supplemental Guarantor / Non-Guarantor Financial Information Condensed Consolidating Statement of Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Revenues [Abstract]
Affiliates	$ 63,187	$ 57,774	[1]	$ 124,699	[1]	$ 114,305	[1]
Third parties	12,098	10,886	[1]	24,884		22,770	[1]
Total revenues	75,285	68,660	[1]	149,583		137,075	[1]
Operating costs and expenses [Abstract]
Operations	24,538	21,907	[1]	50,403		42,382	[1]
Depreciation and amortization	15,127	14,150	[1]	29,281		28,450	[1]
General and administrative	3,100	2,487	[1]	6,332		4,526	[1]
Total operating costs and expenses	42,765	38,544	[1]	86,016		75,358	[1]
Operating income (loss)	32,520	30,116	[1]	63,567		61,717	[1]
Equity in earnings of subsidiaries	0	0		0		0
Equity in earnings of SLC Pipeline	746	794	[1]	1,403		1,625	[1]
Interest Expense	11,629	11,324	[1]	24,113		21,729	[1]
Interest Revenue (Expense), Net		(11,324)				(21,729)
Interest Income	4			107
Other Nonoperating Income (Expense)				2,022
Loss on early extinguishment of debt	0	(383)	[1]	0		(2,979)	[1]
Other Nonoperating Income (Expense), Equity Earnings and Acquisition Costs	(10,879)	(10,913)	[1]	(20,581)		(23,083)	[1]
Income before income taxes	21,641	19,203	[1]	42,986		38,634	[1]
State income tax expense	(344)	(75)		(400)		150
Net Income	21,297	19,128	[1]	42,586		38,484	[1]
Allocation of net loss attributable to Predecessors	0	2,192	[1]	0		4,053	[1]
Allocation of Net Income (Loss) Attributable to Noncontrolling Interest	(1,130)	683	[1]	(4,020)		1,240	[1]
Net Income (Loss) Attributable to Parent	20,167	22,003	[1]	38,566		43,777	[1]
Other comprehensive income (loss)	3,413	(235)	[1]	4,824		685	[1]
Comprehensive income before noncontrolling interest	24,710	21,085	[1]	47,410		43,222	[1]
Comprehensive Income (Loss) net of Noncontrolling Interest	23,580	21,768	[1]	43,390		44,462	[1]
SLC Pipeline [Member]
Operating costs and expenses [Abstract]
Equity in earnings of SLC Pipeline	746	794		1,403		1,625
Parent [Member]
Revenues [Abstract]
Affiliates	0	0		0		0
Third parties	0	0		0		0
Total revenues	0	0		0		0
Operating costs and expenses [Abstract]
Operations	0	0		0		0
Depreciation and amortization	0	0		0		0
General and administrative	983	484		1,791		1,926
Total operating costs and expenses	983	484		1,791		1,926
Operating income (loss)	(983)	(484)		(1,791)		(1,926)
Equity in earnings of subsidiaries	29,413	28,987		56,872		59,647
Interest Expense	(8,263)			(16,515)
Interest Revenue (Expense), Net		(8,309)				(15,018)
Interest Income	0			0
Other Nonoperating Income (Expense)				0
Loss on early extinguishment of debt		(383)				(2,979)
Other Nonoperating Income (Expense), Equity Earnings and Acquisition Costs	21,150	20,295		40,357		41,650
Income before income taxes	20,167	19,811		38,566		39,724
State income tax expense	0	0		0		0
Net Income	20,167	19,811		38,566		39,724
Allocation of net loss attributable to Predecessors		2,192				4,053
Allocation of Net Income (Loss) Attributable to Noncontrolling Interest	0	0		0		0
Net Income (Loss) Attributable to Parent	20,167	22,003		38,566		43,777
Other comprehensive income (loss)	3,413	(235)		4,824		685
Comprehensive income before noncontrolling interest	23,580	21,768		43,390		44,462
Parent [Member] | SLC Pipeline [Member]
Operating costs and expenses [Abstract]
Equity in earnings of SLC Pipeline	0	0		0		0
Guarantor Subsidiaries [Member]
Revenues [Abstract]
Affiliates	60,797	55,263		115,210		109,293
Third parties	10,116	9,752		18,523		20,497
Total revenues	70,913	65,015		133,733		129,790
Operating costs and expenses [Abstract]
Operations	22,104	19,121		45,471		37,262
Depreciation and amortization	11,543	10,562		22,113		21,326
General and administrative	2,117	2,003		4,541		2,600
Total operating costs and expenses	35,764	31,686		72,125		61,188
Operating income (loss)	35,149	33,329		61,608		68,602
Equity in earnings of subsidiaries	(1,234)	(2,046)		2,890		(3,719)
Interest Expense	(3,366)			(7,598)
Interest Revenue (Expense), Net		(3,015)				(6,711)
Interest Income	3			3
Other Nonoperating Income (Expense)				2,022
Loss on early extinguishment of debt		0				0
Other Nonoperating Income (Expense), Equity Earnings and Acquisition Costs	(3,851)	(4,267)		(1,280)		(8,805)
Income before income taxes	31,298	29,062		60,328		59,797
State income tax expense	(344)	(75)		(400)		150
Net Income	30,954	28,987		59,928		59,647
Allocation of net loss attributable to Predecessors		0				0
Allocation of Net Income (Loss) Attributable to Noncontrolling Interest	0	0		0		0
Net Income (Loss) Attributable to Parent	30,954	28,987		59,928		59,647
Other comprehensive income (loss)	3,413	(235)		4,824		685
Comprehensive income before noncontrolling interest	34,367	28,752		64,752		60,332
Guarantor Subsidiaries [Member] | SLC Pipeline [Member]
Operating costs and expenses [Abstract]
Equity in earnings of SLC Pipeline	746	794		1,403		1,625
Non-Guarantor Subsidiaries [Member]
Revenues [Abstract]
Affiliates	2,698	2,776		10,100		5,540
Third parties	1,982	1,134		6,361		2,273
Total revenues	4,680	3,910		16,461		7,813
Operating costs and expenses [Abstract]
Operations	2,742	3,051		5,543		5,648
Depreciation and amortization	3,584	3,588		7,168		7,124
General and administrative	0	0		0		0
Total operating costs and expenses	6,326	6,639		12,711		12,772
Operating income (loss)	(1,646)	(2,729)		3,750		(4,959)
Equity in earnings of subsidiaries	0	0		0		0
Interest Expense	0			0
Interest Revenue (Expense), Net		0				0
Interest Income	1			104
Other Nonoperating Income (Expense)				0
Loss on early extinguishment of debt		0				0
Other Nonoperating Income (Expense), Equity Earnings and Acquisition Costs	1	0		104		0
Income before income taxes	(1,645)	(2,729)		3,854		(4,959)
State income tax expense	0	0		0		0
Net Income	(1,645)	(2,729)		3,854		4,959
Allocation of net loss attributable to Predecessors		0				0
Allocation of Net Income (Loss) Attributable to Noncontrolling Interest	0	0		0		0
Net Income (Loss) Attributable to Parent	(1,645)	(2,729)		3,854		(4,959)
Other comprehensive income (loss)	0	0		0		0
Comprehensive income before noncontrolling interest	(1,645)	(2,729)		3,854		(4,959)
Non-Guarantor Subsidiaries [Member] | SLC Pipeline [Member]
Operating costs and expenses [Abstract]
Equity in earnings of SLC Pipeline	0	0		0		0
Eliminations [Member]
Revenues [Abstract]
Affiliates	(308)	(265)		(611)		(528)
Third parties	0	0		0		0
Total revenues	(308)	(265)		(611)		(528)
Operating costs and expenses [Abstract]
Operations	(308)	(265)		(611)		(528)
Depreciation and amortization	0	0		0		0
General and administrative	0	0		0		0
Total operating costs and expenses	(308)	(265)		(611)		(528)
Operating income (loss)	0	0		0		0
Equity in earnings of subsidiaries	(28,179)	(26,941)		(59,762)		(55,928)
Interest Expense	0			0
Interest Revenue (Expense), Net		0				0
Interest Income	0			0
Other Nonoperating Income (Expense)				0
Loss on early extinguishment of debt		0				0
Other Nonoperating Income (Expense), Equity Earnings and Acquisition Costs	(28,179)	(26,941)		(59,762)		(55,928)
Income before income taxes	(28,179)	(26,941)		(59,762)		(55,928)
State income tax expense	0	0		0		0
Net Income	(28,179)	(26,941)		(59,762)		55,928
Allocation of net loss attributable to Predecessors		0				0
Allocation of Net Income (Loss) Attributable to Noncontrolling Interest	(1,130)	683		(4,020)		1,240
Net Income (Loss) Attributable to Parent	(29,309)	(26,258)		(63,782)		(54,688)
Other comprehensive income (loss)	(3,413)	235		(4,824)		(685)
Comprehensive income before noncontrolling interest	(32,722)	(26,023)		(68,606)		(55,373)
Eliminations [Member] | SLC Pipeline [Member]
Operating costs and expenses [Abstract]
Equity in earnings of SLC Pipeline	$ 0	$ 0		$ 0		$ 0

[1] Restated as described in Note 1.