Derivatives (Details 3) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012
Derivative [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	$ 3,745
Cash Flow Liquid Swap [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	(5,705.0)
Cash Flow Hedges Derivative Instruments at Fair Value, Net	1,693
Swing swap [Member] | Short Contracts [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	(4,588.0)
Derivative Assets (Liabilities), at Fair Value, Net	(35)
Swing swap [Member] | Long Contracts [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	419.0
Derivative Assets (Liabilities), at Fair Value, Net	3
Physical offset to swing swap [Member] | Short Contracts [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	(419.0)
Physical offset to swing swap [Member] | Long Contracts [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	4,588.0
Basis Swap [Member] | Short Contracts [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	(2,501.0)
Derivative Assets (Liabilities), at Fair Value, Net	15
Basis Swap [Member] | Short Contracts [Member] | Liquids [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	(4,393.0)
Derivative Assets (Liabilities), at Fair Value, Net	1,471
Basis Swap [Member] | Long Contracts [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	2,501.0
Derivative Assets (Liabilities), at Fair Value, Net	(30)
Basis Swap [Member] | Long Contracts [Member] | Third Party On System [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	155.0
Physical Offset To Basis Swap [Member] | Third Party On System [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	(155.0)
Derivative Assets (Liabilities), at Fair Value, Net	(22)
Physical Offset To Basis Swap [Member] | Short Contracts [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	(2,501.0)
Derivative Assets (Liabilities), at Fair Value, Net	5,189
Physical Offset To Basis Swap [Member] | Long Contracts [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	2,501.0
Derivative Assets (Liabilities), at Fair Value, Net	(6,624)
Processing Margin Hedges [Member] | Short Contracts [Member] | Gas [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	(187.0)
Derivative Assets (Liabilities), at Fair Value, Net	240
Processing Margin Hedges [Member] | Short Contracts [Member] | Liquids [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	(9,064.0)
Derivative Assets (Liabilities), at Fair Value, Net	4,210
Processing Margin Hedges [Member] | Long Contracts [Member] | Gas [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	1,188.0
Derivative Assets (Liabilities), at Fair Value, Net	(1,035)
Storage Swap [Member] | Short Contracts [Member] | Gas [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	(290.0)
Derivative Assets (Liabilities), at Fair Value, Net	62
Storage Swap [Member] | Short Contracts [Member] | Liquids [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	(4,830.0)
Derivative Assets (Liabilities), at Fair Value, Net	210
Storage Swap [Member] | Long Contracts [Member] | Gas [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	210.0
Derivative Assets (Liabilities), at Fair Value, Net	116
Storage Swap [Member] | Long Contracts [Member] | Liquids [Member]
Derivative [Line Items]
Derivative Nonmonetary Notional Amount	1,470.0
Derivative Assets (Liabilities), at Fair Value, Net	$ (25)