Income Tax (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current income tax (benefit) expense:
Federal	$ (11,078,000)	$ (2,964,000)	$ 15,039,000
State	(130,000)	598,000	2,539,000
Total current	(11,208,000)	(2,366,000)	17,578,000
Deferred income tax expense (benefit):
Federal	24,382,000	38,531,000	(4,732,000)
State	(505,000)	2,163,000	803,000
Total deferred	23,877,000	40,694,000	(3,929,000)
Total provision for income tax	12,669,000	38,328,000	13,649,000
Income Tax
Income before provision for income tax	53,114,000	255,293,000	118,449,000
Federal statutory income tax rate (as a percent)	35.00%	35.00%	35.00%
Federal income tax at statutory rate	10,901,000	25,967,000	1,335,000
Permanent items	40,000	28,000	36,000
State income taxes, net of federal benefit	(690,000)	2,377,000	2,844,000
Current year change in valuation allowance		(5,000)	(64,000)
Prior period adjustments and tax rate changes	(147,000)	(2,517,000)	163,000
Provision on income from Class A units	2,617,000	12,412,000	9,323,000
Other	(52,000)	66,000	12,000
Total provision for income tax	12,669,000	38,328,000	13,649,000
Oldest open tax year	2009
Liability for uncertain tax positions	0	0	0
Current deferred tax assets:
Accruals and reserves	221,000	98,000
Derivative instruments	4,845,000	5,183,000
Net operating loss carryforward	18,134,000
Capital loss carryforward	904,000
State tax credit	74,000
Current deferred tax assets	24,178,000	5,281,000
Valuation allowance	(978,000)
Deferred income taxes	23,200,000	5,281,000
Long-term deferred tax assets:
Accruals and reserves	329,000	113,000
Derivative instruments	10,102,000	9,915,000
Phantom unit compensation	3,328,000	2,624,000
Capital loss carryforward		904,000
Net operating loss carryforward	9,283,000	1,000
Long-term deferred tax assets	23,042,000	13,557,000
Valuation allowance		(904,000)
Net long-term deferred tax assets	23,042,000	12,653,000
Long-term deferred tax liabilities:
Property, plant and equipment and intangibles	(4,755,000)	(3,861,000)
Investment in affiliated groups	(305,853,000)	(198,220,000)
Long-term deferred tax liabilities	(310,608,000)	(202,081,000)
Long-term subtotal	(287,566,000)	(189,428,000)
Net deferred tax liability	(264,366,000)	(184,147,000)
Federal
Income Tax
NOL carryforwards expiration period	20 years
State | Minimum
Income Tax
NOL carryforwards expiration period	5 years
State | Maximum
Income Tax
NOL carryforwards expiration period	20 years
Corporation
Deferred income tax expense (benefit):
Total provision for income tax	12,630,000	36,639,000	10,907,000
Income Tax
Income before provision for income tax	31,145,000	74,192,000	3,813,000
Federal statutory income tax rate (as a percent)	35.00%	35.00%	35.00%
Federal income tax at statutory rate	10,901,000	25,967,000	1,335,000
Permanent items	40,000	28,000	36,000
State income taxes, net of federal benefit	(729,000)	688,000	102,000
Current year change in valuation allowance		(5,000)	(64,000)
Prior period adjustments and tax rate changes	(147,000)	(2,517,000)	163,000
Provision on income from Class A units	2,617,000	12,412,000	9,323,000
Other	(52,000)	66,000	12,000
Total provision for income tax	12,630,000	36,639,000	10,907,000
Amount of tax deductions related to equity compensation in excess of compensation	600,000
Valuation allowance as a percentage of long-term deferred tax asset attributable to capital loss carryforwards or state tax credit	100.00%
Corporation | Federal
Income Tax
Net operating loss carryforwards	26,500,000
Corporation | State
Income Tax
Net operating loss carryforwards	1,500,000
Partnership
Deferred income tax expense (benefit):
Total provision for income tax	39,000	1,689,000	2,742,000
Income Tax
Income before provision for income tax	42,131,000	178,817,000	122,642,000
Federal statutory income tax rate (as a percent)	0.00%	0.00%	0.00%
State income taxes, net of federal benefit	39,000	1,689,000	2,742,000
Total provision for income tax	39,000	1,689,000	2,742,000
Eliminations
Income Tax
Income before provision for income tax	$ (20,162,000)	$ 2,284,000	$ (8,006,000)
Federal statutory income tax rate (as a percent)	0.00%	0.00%	0.00%